Inhibitor of heat shock protein 90 (Hsp90) chaperone activity, and an analog of geldanamycin (Cat. No. 1368). Subsequently inhibits the activity of oncogenic proteins such as p185erbB-2 (IC50 = 31 nM), N-ras, Ki-ras and c-Akt. Antitumor in vivo. Also protects neuroprogenitor cells against stress-induced apoptosis at low concentrations (10 nM) in vitro. Purity 98%. MW (observed): 585.7