Tetradecanoylphorbol acetateis a 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 is also commonly used together with ionomycin to stimulate T-cell activation, proliferation, and cytokine production, and is used in protocols for intracellular staining of these cytokines.