Potent antitumor antibiotic. Inhibitor of pp60src tyrosine kinase and of c-myc gene expression in murine lymphoblastoma cells. Inhibits the transforming activity of abl, erbB, fps, src, and yes. Binds specifically to heat shock protein 90 (HSP90) and to its endoplasmic reticulum homolog GP96 (GRP94). Capable of destabilizing several oncogene and proto-oncogene products. Potent inhibitor of the nuclear hormone receptor family. Protects against α-synuclein toxicity to dopaminergic neurons in Drosophila. Destabilizes mutant p53 protein from a number of breast, leukemic, and prostate cell lines. Inhibits basal and hypoxia-induced expression of c-Jun (IC50=75nM) and abolishes hypoxia-induced increase in c-Jun N-terminal kinase (JNK) activity. Purity: ≥95% (HPLC). Solubility: Soluble in DMSO (10mg/ml); insoluble in water. Long Term Storage: -20°C.