pubmed-article:3813653 | pubmed:abstractText | 12-o-Tetradecanoylphorbol-13-acetate (TPA) activates calcium-activated, phospholipid-dependent protein kinase (protein kinase C) partially purified in an ion exchange column from pig epidermis. Protein kinase C was activated by TPA in a concentration-dependent manner with simultaneous addition of Ca2+ and phospholipid. Polyprenoic acid derivative (E5166) which is a newly synthesized retinoic acid derivative, inhibited the TPA activation of protein kinase C. This inhibition may explain the mechanisms by which retinoids inhibit TPA-induced tumor promotion. | lld:pubmed |