Radicicol inhibits src (IC50=0.27µM) and src-like kinases(1), leading to hypophosphorylation of retinoblastoma tumor suppressor protein(2). It causes morphological reversion of ras-transformed cells(3) and leads to selective depletion of Raf kinase(4). It also displays anti-angiogenic activity(5), and binds to and inhibits Hsp 90 molecular chaperone(6). It binds more strongly to Hsp90 than to GRP94. It also binds to yeast HSP90, E. coli HtpG and TRAP-1. Looking for more information on HSP90? Visit our new HSP90 Scientific Resource Guide at http://www.HSP90.ca.