Filed by Prosperity Bancshares, Inc.

Pursuant to Rule 425 under the

Securities Act of 1933

Subject Companies: East Texas Financial Services, Inc. and

American State Financial Corporation

Commission File No. 1-35388

PRESS RELEASE

For more information contact:

Prosperity Bancshares, Inc.®	Dan Rollins
Prosperity Bank Plaza	President and Chief Operating Officer
4295 San Felipe	281.269.7199
Houston, Texas 77027	dan.rollins@prosperitybanktx.com

FOR IMMEDIATE RELEASE

PROSPERITY BANCSHARES, INC.^®

COMPLETES ACQUISITION OF

THE BANK ARLINGTON

HOUSTON, April 2, 2012. Prosperity Bancshares, Inc.^® (NYSE: PB) completed the previously announced acquisition of The Bank Arlington on April 1, 2012. The transaction continues Prosperity’s strategic growth and expansion of the franchise in the Dallas-Fort Worth Metroplex.

Prosperity, which began trading on the New York Stock Exchange (NYSE) under the symbol “PB” on December 28, 2011, was recently named the #1 bank in America by Forbes in their “2012 Best Banks in America” report.

Pursuant to the terms of the reorganization agreement, Prosperity will issue up to 135,389 shares of Prosperity common stock for all outstanding shares of The Bank Arlington capital stock, plus cash in lieu of fractional shares.

The Bank Arlington operates one (1) banking office in Arlington, Texas, in the Dallas-Fort Worth Metroplex. Prosperity will now operate thirty-two (32) banking centers in the Dallas-Fort Worth area. As of December 31, 2011, The Bank Arlington reported total assets of $37.3 million, total loans of $21.3 million and total deposits of $32.8 million.

Prosperity Bancshares, Inc.^®

Prosperity Bancshares Inc.^®, recently named “America’s Best Bank” by Forbes, is a $9.8 billion Houston, Texas based regional financial holding company, formed in 1983. Operating under a community banking philosophy and seeking to develop broad customer relationships based on service and convenience, Prosperity offers a variety of traditional loan and deposit products to its customers, which consist primarily of small and medium sized businesses and consumers. In addition to established banking products, Prosperity offers a complete line of services including: Internet Banking services at http://www.prosperitybanktx.com, Retail Brokerage Services, MasterMoney Debit Cards, and 24 hour voice response banking. Prosperity currently operates one hundred seventy six (176) full service banking locations; sixty (60) in the Houston area; twenty (20) in the South Texas area including Corpus Christi and Victoria; thirty-two (32) in the Dallas/Fort Worth area; twenty-one (21) in the East Texas area; thirty-four (34) in the Central Texas area including Austin and San Antonio; and ten (10) in the Bryan/College Station area.

In connection with the proposed merger of East Texas Financial Services, Inc. into Prosperity, Prosperity has filed with the Securities and Exchange Commission a registration statement on Form S-4 to register the shares of Prosperity’s common stock to be issued to the stockholders of East Texas Financial Services. The registration statement includes a proxy statement/prospectus which has been sent to the stockholders of East Texas Financial Services seeking their approval of the proposed transaction.

WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE REGISTRATION STATEMENT ON FORM S-4, THE PROXY STATEMENT/PROSPECTUS INCLUDED WITHIN THE REGISTRATION STATEMENT ON FORM S-4 AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE PROPOSED TRANSACTION BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT PROSPERITY, EAST TEXAS FINANCIAL SERVICES AND THE PROPOSED TRANSACTION.

In connection with the proposed merger of American State Financial Corporation into Prosperity, Prosperity will file with the Securities and Exchange Commission a registration statement on Form S-4 to register the shares of Prosperity’s common stock to be issued to the shareholders of American State Financial Corporation. The registration statement will include a proxy statement/prospectus which will be sent to the shareholders of American State Financial Corporation seeking their approval of the proposed transaction.

WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE REGISTRATION STATEMENT ON FORM S-4, THE PROXY STATEMENT/PROSPECTUS INCLUDED WITHIN THE REGISTRATION STATEMENT ON FORM S-4 AND ANY OTHER RELEVANT DOCUMENTS TO BE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE PROPOSED TRANSACTION BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT PROSPERITY, AMERICAN STATE FINANCIAL CORPORATION AND THE PROPOSED TRANSACTION.

Investors and security holders may obtain free copies of these documents through the website maintained by the Securities and Exchange Commission at http://www.sec.gov. Documents filed with the SEC by Prosperity will be available free of charge by directing a request by telephone or mail to Prosperity Bancshares, Inc., Prosperity Bank Plaza, 4295 San Felipe, Houston, Texas 77027 Attn: Investor Relations. Prosperity’s telephone number is (281) 269-7199.

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“Safe Harbor” Statement under the Private Securities Litigation Reform Act of 1995: This release contains, and the remarks by Prosperity’s management on the conference call may contain, forward-looking statements within the meaning of the securities laws that are based on current expectations, assumptions, estimates and projections about Prosperity, and its subsidiaries. These forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties, many of which are outside of Prosperity’s control, that may cause actual results to differ materially from those expressed or implied by the forward-looking statements. These risks and uncertainties include but are not limited to whether Prosperity can: successfully identify acquisition targets and integrate the businesses of acquired companies and banks; continue to sustain its current internal growth rate or total growth rate; provide products and services that appeal to its customers; continue to have access to debt and equity capital markets; and achieve its sales objectives. Other risks include, but are not limited to: the possibility that credit quality could deteriorate; actions of competitors; changes in laws and regulations (including changes in governmental interpretations of regulations and changes in accounting standards); a deterioration or downgrade in the credit quality and credit agency ratings of the securities in Prosperity’s securities portfolio; customer and consumer demand, including customer and consumer response to marketing; effectiveness of spending, investments or programs; fluctuations in the cost and availability of supply chain resources; economic conditions, including currency rate fluctuations and interest rate fluctuations; weather; and the stock price volatility associated with “small-cap” companies. These and various other factors are discussed in Prosperity’s Annual Report on Form 10-K for the year ended December 31, 2011 and other reports and statements Prosperity has filed with the SEC. Copies of the SEC filings for Prosperity Bancshares, Inc.^® may be downloaded from the Internet at no charge from www.prosperitybanktx.com.