12-O-Tetradecanoylphorbol-13-acetate

12-O-tetradecanoylphorbol-13-acetate (TPA), also commonly known as tetradecanoylphorbol acetate, tetradecanoyl phorbol acetate, and phorbol 12-myristate 13-acetate (PMA), is diester of phorbol and 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 result from its similarity to one of the natural activators of classic PKC isoforms, diacylglycerol. TPA is a small molecule drug.

TPA is also being studied as a drug in the treatment of hematologic cancer.

TPA has a specific use in cancer diagnostics as a B-cell specific mitogen in cytogenetic testing. To view the chromosomes, a cytogenetic test requires dividing cells. TPA is used to stimulate division of B-cells during cytogenetic diagnosis of B-cell cancers such as chronic lymphocytic leukemia.

TPA was first found in the croton plant, a shrub found in Southeast Asia, exposure to which provokes a poison ivy-like rash. It underwent a phase 1 clinical trial.