Radicicol, a microbial cell differentiation modulator originally extracted from Neocosmospora tenuicristata, has been shown to inhibit proliferation and plasminogen activator production by vascular endothelial cells. Radicicol inhibits the expression of Cox-2 (IC50 = 27 nM) without affecting Cox-1 expression in LPS-stimulated macrophages. It is also a potent inhibitor of Hsp90. Experiments sμggest that radicicol reduces the intracellular level of autophosphorylation of p60v-src as well as other tyrosine-phosphorylated proteins via inhibition of SRC kinases. In addition, radicicol has demonstrated the ability to inhibit K-ras signaling pathway which includes phosphorylation of Raf-1, MAPKK, and MAPK.A potent inhibitor of Hsp90, SRC, and Cox-2 Radicicol, a microbial cell differentiation modulator originally extracted from Neocosmospora tenuicristata, has been shown to inhibit proliferation and plasminogen activator production by vascular endothelial cells. Radicicol inhibits the expression of Cox-2 (IC50 = 27 nM) without affecting Cox-1 expression in LPS-stimulated macrophages. It is also a potent inhibitor of Hsp90. Experiments suggest that radicicol reduces the intracellular level of autophosphorylation of p60v-src as well as other tyrosine-phosphorylated proteins via inhibition of SRC kinases. In addition, radicicol has demonstrated the ability to inhibit K-ras signaling pathway which includes phosphorylation of Raf-1, MAPKK, and MAPK. A potent inhibitor of Hsp90, SRC, and Cox-2