PF-04929113 Mesylate (also known as SNX-5422) is a potent, selective inhibitor of heat shock protein 90 (Hsp90), a molecular chaperone involved in the folding and stabilization of proteins critical for cell growth and survival. It is primarily used in medical research, particularly in oncology, to study cancer therapeutics. By inhibiting Hsp90, it disrupts signaling pathways that promote tumor proliferation, such as those involving oncogenic proteins like HER2, BRAF, and AKT. Researchers employ this compound in preclinical models to evaluate its effects on tumor growth, metastasis, and efficacy in combination therapies, contributing to the development of targeted treatments for various cancers including solid tumors and lymphomas.