Microorganisms and plants are treasuries of secondary metabolites having unique structures and biological activities. We have isolated inhibitors of cellular signal transduction from them. Phosphatidylinositol turnover inhibitors include inostamycin, piericidins and echiguanines. Erbstatin and lavendustin A were isolated as tyrosine kinase inhibitors, and dephostatin was isolated as a tyrosine phosphatase inhibitor. Recently, we have isolated a new vinca alkaloid having anti-ras activity. These signal transduction inhibitors will be useful for mechanistic studies and suppression of cancer.
