PRRT2 and neoplasm: Other naturally occurring phorbols, like prostratin, activate PKC but lack the tumor-promoting activity that makes PMA unsuitable for biomedical research (Szallasi and Blumberg, 1991b); rather than that, prostratin has shown some tumor-supressing activity (Shen et al., 2015), but it is best known for its antiviral properties, particularly against HIV (see Miana et al., 2015 for a recent review).