press release archive

Rigel Announces Presentations at the 96th Annual Meeting of the American Association for Cancer Research (AACR)

South San Francisco, CA - April 15, 2005

Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL - News) today announced that two presentations related to its cancer research will be made at the 96th Annual Meeting of the American Association for Cancer Research (AACR), taking place April 16-20 in Anaheim, California.

Details are as follows:

Presentation Time:		Monday, April 18, 8:00 am - 12:00 pm
Presentation Number:		2019
Title:		Requirement for the tyrosine kinase Axl in angiogenesis and tumor growth
Presentation Time:		Wednesday, April 20, 8:00 a.m. - 12:00 p.m.
Presentation Number:		5469
Title:		Critical role of the ubiquitin Ligase activity of Np95, a nuclear RING finger protein, in tumor cell growth

Rigel is investigating both the kinase system and the ubiquitin ligase system for the discovery of potential novel cancer therapeutics. Rigel has discovered potent and highly selective small molecule inhibitors of selected kinases and ubiquitin ligases. Some of these inhibitors have shown positive activity in animal models of cancer and are in preclinical development at Rigel. Rigel has collaborations with Merck, Inc. and Daiichi Pharmaceuticals on selected ligase targets in cancer.

About Ubiquitin Ligases
Ubiquitin ligases are enzymes that regulate protein degradation within the cell. The breakdown of proteins, in turn, affects many important cellular functions, including cell division. Targeting ligases represents a novel approach to treating diseases where normal cellular processes are out of balance. Because unchecked cell division is the hallmark of cancer, researchers believe that this part of the cell machinery represents a particularly compelling target for cancer therapies. Ubiquitin ligase targets are numerous and modular. This provides the potential for intervening in a highly specific fashion in a disease, potentially improving efficacy and minimizing side effects.

About Rigel (www.rigel.com)
Rigel's mission is to become a source of novel, small-molecule drugs to address large, unmet medical needs. We have four research and development programs investigating treatments for asthma/allergy, rheumatoid arthritis, hepatitis C and oncology. Our strategy is to initiate clinical trials with at least one new product candidate annually and to pursue partnerships with pharmaceutical and biotechnology companies for late-stage clinical development and commercialization of those product candidates.

This press release contains "forward-looking" statements, including statements related to Rigel's plans to pursue clinical development of product candidates and the timing thereof and the potential efficacy of product candidates. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "plans," "intends," "expects" and similar expressions are intended to identify these forward-looking statements. There are a number of important factors that could cause Rigel's results to differ materially from those indicated by these forward-looking statements, including risks associated with the timing and success of clinical trials and the commercialization of product candidates, as well as other risks detailed from time to time in Rigel's SEC reports, including its Annual Report on Form 10-K for the year ended December 31, 2004. Rigel does not undertake any obligation to update forward-looking statements.