Pendolmycin is a new indole alkaloid isolated from Nocardiopsis as an inhibitor of phosphatidylinositol turnover. Structurally, pendolmycin is similar to teleocidin B and lyngbyatoxin A. Pendolmycin, teleocidin B and 12-O-tetradecanoylphorbol-13-acetate all inhibited phosphatidylinositol turnover in A431 cells. Pendolmycin inhibited binding of epidermal growth factor, activated arachidonic acid release and hexose transport, and inhibited binding of phorbol-12,13-dibutylate in C3H10T1/2 cells. Thus, pendolmycin was as potent as teleocidin B and phorbol ester tumor promoters in modification of cell membrane functions, while having the simplest structure among them.