Cytokinetics Announces Phase I Results for SB-715992 to be Presented at the 2004 Annual Meeting Of The American Society of Clinical Oncology

South San Francisco, CA - June 2, 2004

Cytokinetics, Inc. (Nasdaq: CYTK) announced today that the results of two Phase I studies for SB-715992 conducted by GlaxoSmithKline will be presented at the 2004 Annual Meeting of the American Society of Clinical Oncology (ASCO) in New Orleans. These oral and poster presentations focus on the safety and tolerability of SB-715992, a novel small molecule inhibitor of kinesin spindle protein (KSP), a mitotic kinesin protein essential for proper cell division. SB-715992 is the lead drug candidate in clinical development arising from a broad strategic collaboration between Cytokinetics and GlaxoSmithKline to discover, develop and commercialize novel small molecule therapeutics targeting human mitotic kinesins for applications in the treatment of cancer and other diseases. GlaxoSmithKline has initiated a broad Phase II clinical trial program for SB-715992.

Abstracts being presented

These abstracts will be available upon request or through the ASCO website (www.asco.org):

1. Abstract #2004: Phase I Trial of Novel Kinesin Spindle Protein (KSP) Inhibitor SB-715992 IV days 1, 8, 15 Q 28 Days. (Oral presentation by Howard A. Burris III, The Sarah Cannon Cancer Center, Nashville, TN, on Sunday, June 6, 2004, Hall I1, 7:45 AM – 10:45 AM).

2. Abstract #2078: Phase I Trial of Novel Kinesin Spindle Protein (KSP) Inhibitor SB-715992 IV Q 21 Days. (Poster presentation by Quincy S. Chu, Cancer Therapy & Research Center (CTRC), San Antonio, TX, on Monday, June 7, 2004, Hall A (right half), 8:00 AM – 12:00 PM).

About Cytokinetics

Cytokinetics is a leading biopharmaceutical company focused on the discovery, development and commercialization of novel small molecule drugs that specifically target the cytoskeleton. The cytoskeleton is a complex biological infrastructure that plays a fundamental role within every human cell. Cytokinetics’ focus on the cytoskeleton enables it to develop novel and potentially safer and more effective classes of drugs directed at treatments for cancer, cardiovascular disease, fungal diseases and other diseases. Cytokinetics has developed a cell biology driven approach and proprietary technologies to evaluate the function of many interacting proteins in the complex environment of the intact human cell. Cytokinetics employs the PUMA™ system and Cytometrix™ technologies to enable early identification and automated prioritization of compounds that are highly selective for their intended protein targets without other cellular effects, and are thereby less likely to give rise to clinical side effects. Cytokinetics and GlaxoSmithKline have entered into a strategic alliance to discover, develop and commercialize small molecule therapeutics targeting human mitotic kinesins for applications in the treatment of cancer and other diseases. GlaxoSmithKline is conducting Phase II clinical trials for SB-715992 and a Phase I clinical trial with SB-743921, each a drug candidate that has emerged from the strategic alliance. Additional information about Cytokinetics can be obtained at www.cytokinetics.com.

This press release contains forward-looking statements for purposes of the Private Securities Litigation Reform Act of 1995 and it is the Company’s intent that such statements be protected by the safe harbor created thereby. Examples of such statements include, but are not limited to, statements relating to the potential benefits of the Company’s drug candidates. Such statements are based on management’s current expectations, but actual results may differ materially due to various factors. Such statements involve risks and uncertainties, including, but not limited to, those risks and uncertainties relating to difficulties or delays in development, testing, regulatory approval, production and marketing of the Company’s drug candidates that could slow or prevent product approval or market acceptance (including the risk that uncertainty of patent protection for the Company’s intellectual property or trade secrets, the Company’s ability to obtain additional financing if necessary and unanticipated research and development and other costs). For further information regarding these and other risks related to the Company’s business, investors should consult the Company’s filings with the Securities and Exchange Commission. Cytokinetics does not undertake any obligation to update forward-looking statements.