A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer.
Immunosuppression is a reduction of the activation or efficacy of the immune system.
Sigma-Aldrich Corporation is an American life science and high technology company with over 9,600 employees and operations in 40 countries.
Tumor initiation is defined as "a process in which normal cells are changed so that they are able to form tumors".
Tumor promotion is a process in carcinogenesis by which various factors permit the descendents of a single initiated cell to survive and expand in number, i.e. to resist apoptosis and to undergo clonal growth.
12-O-Tetradecanoylphorbol-13-acetate (TPA), also commonly known as tetradecanoylphorbol acetate, tetradecanoyl phorbol acetate, and phorbol 12-myristate 13-acetate (PMA), is a diester of phorbol and a potent tumor promoter often employed in biomedical research to activate the signal transduction enzyme protein kinase C (PKC).