O-Tetradecanoylphorbol-13-acetate (TPA), also commonly known as phorbol 12-myristate 13-acetate (PMA), is a potent tumor promoter often employed in biomedical research to activate the signal transduction enzyme protein kinase C (PKC). The effects of TPA on PKC results from its similarity to one of the natural activators of classic PKC isoforms, diacylglycerol. TPA is also being studied as a drug in the treatment of hematologic cancer.