CUB has agreed, among other things, to covenants relating to
(x)obligations to facilitate CUBs shareholders consideration
of, and voting upon, the approval of the principal terms of the
Merger Agreement and certain related matters as applicable,
(y)the recommendations by the board of directors of CUB in
favor of the approval by CUBs shareholders of the principal
terms of the Merger Agreement and certain related matters as
applicable and (z)non-solicitation obligations relating to
alternative business combination transactions.

Completion of the Merger is subject to certain customary
conditions, including (i)approval by CUBs shareholders, (ii)the
absence of any governmental order or law prohibiting the
consummation of the Merger and (iii)effectiveness of the
registration statement for the PacWest Common Stock to be
issued as consideration in the Merger. The obligation of each
party to consummate the Merger is also conditioned upon
(a)subject to certain exceptions, the accuracy of the
representations and warranties of the other party,
(b)performance in all material respects by the other party of
its obligations under the Merger Agreement, (c)receipt by each
party of a tax opinion to the effect that the Merger will
qualify as a reorganization within the meaning of
Section368(a)of the Internal Revenue Code of 1986, as amended,
and (d)the absence of a material adverse effect with respect to
the other party since the date of the Merger Agreement. The
obligation of PacWest to consummate the Merger is also
conditioned upon (w)the adjusted shareholders equity of CUB and
CUBs allowance for loan losses being in excess of specified
levels, (x)the receipt of required regulatory approvals and
such approvals not containing materially burdensome regulatory
conditions, (y)the holders of not more than ten percent of the
outstanding CUB Common Shares having duly exercised their
dissenters rights under California law and (z)the consummation
of the Preferred Stock Purchase. The obligation of CUB to
consummate the Merger is also conditioned upon the receipt of
certain required regulatory approvals.

The Merger Agreement contains certain termination rights for
both PacWest and CUB, including if (i)the Merger is not
consummated by February28, 2018 (as it may be extended to
April30, 2018 under certain circumstances, the End
Date), (ii)the necessary regulatory approvals are not
obtained, (iii)the approval of CUBs shareholders is not
obtained, or (iv)there has been a breach by the other party
that is not cured such that the applicable closing conditions
are not satisfied. In addition, in certain circumstances,
PacWest may terminate the Merger Agreement prior to CUBs
shareholder approval of the Merger in the event that (A)CUB
materially breaches its non-solicitation obligations relating
to alternative business combination transactions, (B)CUBs board
withdraws or adversely modifies its recommendation to
shareholders or fails to affirm its recommendation within the
required time period after an acquisition proposal is made or
(C)CUBs board recommends a tender offer or fails to recommend
against such tender offer within ten business days after
commencement. The Merger Agreement also provides that CUB will
be obligated to pay a termination fee of $26.5million to
PacWest if the Merger Agreement (i)is terminated by PacWest in
the

circumstances described in the preceding sentence or (ii)(A)if
an acquisition proposal is made to CUB or to its shareholders
publicly, (B)the Merger Agreement is terminated for failure to
consummate the Merger by the End Date without the approval of
CUBs shareholders being obtained or for failure to obtain the
approval of CUBs shareholders and (C)CUB enters into a
definitive agreement with respect to or consummates certain
acquisition proposals within 12 months of termination of the
Merger Agreement.

In addition, the Merger Agreement may be terminated by CUB in
the event that (i)the volume weighted average price of shares
of PacWest Common Stock quoted on NASDAQ for the Determination
Period (as defined below) (the PacWest Average Closing
Price) is less than $44.84 per share and (ii)the PacWest
Average Closing Price for the Determination Period
underperforms the KBW Regional Banking Index by greater than
15%. If CUB exercises its termination right described in the
preceding sentence, PacWest will have the option of reinstating
the Merger and, in its sole discretion, either adjusting the
Exchange Ratio or adding cash to the per share Cash
Consideration, determined in accordance with the Merger
Agreement. The Merger Agreement defines Determination
Period as the period beginning on the day that is twenty
(20) consecutive trading days prior to the fifth (5th) business
day immediately prior to the closing date of the Merger (the
Determination Date) and ending on the Determination Date

The Merger Agreement and the above description of the Merger
Agreement have been included to provide investors and security
holders with information regarding the terms of the Merger
Agreement. The Merger Agreement and the above description are
not intended to provide any other factual information about
PacWest, CUB, or their respective subsidiaries or affiliates.
The representations, warranties and covenants contained in the
Merger Agreement were made only for purposes of the Merger
Agreement and as of specific dates, were solely for the benefit
of the parties to the Merger Agreement, may be subject to
limitations agreed upon by the parties, including being
qualified by confidential disclosures made by each contracting
party to the other for the purposes of allocating contractual
risk between them rather than establishing these matters as
facts and may be subject to standards of materiality applicable
to the contracting parties that differ from those applicable to
investors. Investors should not rely on the representations,
warranties and covenants or any description thereof as
characterizations of the actual state of facts or condition of
PacWest, CUB or any of their respective subsidiaries,
affiliates or businesses. Moreover, information concerning the
subject matter of the representations, warranties and covenants
may change after the date of the Merger Agreement, which
subsequent information may or may not be fully reflected in
public disclosures by PacWest or CUB. Accordingly, investors
should read the representations and warranties in the Merger
Agreement not in isolation but only in conjunction with the
other information about PacWest or CUB and their respective
subsidiaries that the respective companies include in reports,
statements and other filings they make with the Securities and
Exchange Commission (the SEC).

Voting Agreements

PacWest also entered into voting agreements with each of the
directors of CUB, as shareholders of CUB. The voting agreements
generally require such shareholders to vote all of their CUB
Common Shares in favor of the approval of the principal terms
of the Merger Agreement and certain related matters as
applicable and against alternative transactions and generally
prohibit them from transferring their shares, subject to
certain exceptions. The voting agreements will terminate in
certain circumstances, including upon the consummation of the
Merger or the termination of the Merger Agreement in accordance
with its terms.

Non-Solicitation Agreements

PacWest also entered into non-solicitation agreements with each
director of CUB in connection with the Merger Agreement, to
which such directors are subject to certain customary
non-solicitation restrictions.

Consulting Agreements

In connection with the Merger Agreement, PacWest entered into
consulting agreements with, among others, David I. Rainer, the
chairman and chief executive officer of CUB, and K. Brian
Horton, director and president of CUB, whereby PacWest will
retain Mr.Rainer and Mr.Horton as consultants to perform
certain transitional services for PacWest beginning on the
first business day following the closing of the Merger and
ending on the earlier of (A)(1)the four year anniversary of the
closing of the Merger, in the case of Mr.Rainer, or (2)the two
year anniversary of the closing of the Merger, in the case of
Mr.Horton, or (B)the termination of such consulting agreement
to the terms therein. The effectiveness of the consulting
agreements is conditioned upon the consummation of the Merger.

The foregoing descriptions of the Merger Agreement, the voting
agreements and the non-solicitation agreements do not purport
to be complete and are qualified in their entirety by reference
to the respective agreements attached hereto as Exhibits 2.1,
99.1, and 99.2, respectively, which are incorporated by
reference herein.

Item 8.01 Other Events

On April6, 2017, PacWest and CUB issued a joint press release
announcing that they had entered into the Merger Agreement, a
copy of which is attached hereto as Exhibit99.3 and
incorporated herein by reference. In addition, PacWest and CUB
will be providing supplemental information regarding the Merger
in connection with a presentation to investors. The slides to
be used in connection with this investor presentation are
attached hereto as Exhibit99.4 and are incorporated herein by
reference.

Forward-Looking Statements

This communication contains certain forward-looking information
about PacWest, CUB, and the combined company after the close of
the Merger and the Bank Merger that is intended to be covered
by the safe harbor for forward-looking statements provided by
the Private Securities Litigation Reform Act of 1995. All
statements other than statements of historical fact are
forward-looking statements. Such statements involve inherent
risks, uncertainties, and contingencies, many of which are
difficult to predict and are generally beyond the control of
PacWest, CUB and the combined company. PacWest cautions readers
that a number of important factors could cause actual results
to differ materially from those expressed in, or implied or
projected by, such forward-looking statements. In addition to
factors previously disclosed in reports filed by PacWest and
CUB with the SEC, risks and uncertainties for each institution
and the combined institution include, but are not limited to:
lower than expected revenues, credit quality deterioration or a
reduction in real estate values could cause an increase in the
provision for credit losses and allowance for credit losses and
a reduction in net earnings, increased competitive pressure
among depository institutions, the ability to complete the
Merger and the Bank Merger, including by obtaining regulatory
approvals and approval by the shareholders of CUB, or any
future transaction, successfully integrate such acquired
entities, or achieve expected beneficial synergies and/or
operating efficiencies, in each case within expected
time-frames or at all, regulatory approvals may not be received
on expected timeframes or at all, the possibility that
personnel changes/retention will not proceed as planned, the
possibility that a change in the interest rate environment may
reduce net interest margins, higher than anticipated operating
expenses, the effectiveness of our risk management framework,
asset/liability re-pricing risks and liquidity risks, the costs
and effects of legal, compliance, and regulatory actions,
changes and developments, including the impact of adverse
judgments or settlements in litigation, the initiation and
resolution of regulatory or other governmental inquiries or
investigations, and/or the results of regulatory examinations
or reviews, general economic conditions, either nationally or
in the market areas in which the entities operate or anticipate
doing business, are less favorable than expected, and other
risk factors described in documents filed by PacWest and CUB
with the SEC.

All forward-looking statements included in this communication
are based on information available at the time of the
communication. Pro forma, projected and estimated numbers are
used for illustrative purposes only and are not forecasts, and
actual results may differ materially.

We are under no obligation to (and expressly disclaim any such
obligation to) update or alter our forward-looking statements,
whether as a result of new information, future events or
otherwise except as required by law.

Additional Information About the Proposed Transaction
and Where to Find It

Investors and security holders are urged to carefully review
and consider each of PacWests and CUBs public filings with the
SEC, including but not limited to their Annual Reports on
Form10-K, their proxy statements, their Current Reports on
Form8-K and their Quarterly Reports on Form10-Q. The documents
filed by PacWest with the SEC may be obtained free of charge at
PacWests website at www.pacwestbancorp.com or at the SECs
website at www.sec.gov. These documents may also be obtained
free of charge from PacWest by requesting them in writing to
PacWest Bancorp, 9701 Wilshire Boulevard, Suite700, Beverly
Hills, California 90212; Attention: Investor Relations, by
telephone at (310) 887-8521 or via e-mail to
[email protected].

The documents filed by CUB with the SEC may be obtained free of
charge at CUBs website at www.cubancorp.com or at the SECs
website at www.sec.gov. These documents may also be obtained
free of charge from CUB by requesting them in writing to CU
Bancorp, 818 W. 7th Street, Suite220, Los Angeles, California
90017; Attention: Investor Relations, or by telephone at (818)
257-7700.

PacWest intends to file a registration statement with the SEC
which will include a proxy statement of CUB and a prospectus of
PacWest, and each party will file other documents regarding the
proposed transaction with the SEC. Before making any voting or
investment decision, investors and security holders of CUB are
urged to carefully read the entire registration statement and
proxy statement/prospectus, when they become available, as well
as any amendments or supplements to these documents, because
they will contain important information about the proposed
transaction. A definitive proxy statement/prospectus
will be sent to the shareholders of CUB seeking any required
shareholder approvals. Investors and security holders will be
able to obtain the registration statement and the proxy
statement/prospectus free of charge from the SECs website or
from PacWest or CUB by writing to the addresses provided for
each company set forth in the paragraphs above.

PacWest, CUB, their directors, executive officers and certain
other persons may be deemed to be participants in the
solicitation of proxies from CUB shareholders in favor of the
approval of the transaction. Information about the directors
and executive officers of PacWest and their ownership of
PacWest common stock is set forth in the proxy statement for
PacWests 2017 annual meeting of stockholders, as previously
filed with the SEC. Information about the directors and
executive officers of CUB and their ownership of CUB Common
Shares is set forth in the proxy statement for CUBs 2016 annual
meeting of shareholders, as previously filed with the SEC.
Shareholders may obtain additional information regarding the
interests of such participants by reading the registration
statement and the proxy statement/prospectus when they become
available.

Item 9.01 Financial Statements and Exhibits.

(d)Exhibits.

*Schedules and exhibits omitted to Item 601(b)(2)of Regulation
S-K. PacWest agrees to furnish supplementally a copy of any
omitted schedule or exhibit to the SEC upon request.