Tumor Promoter-Stimulated Protein Phosphorylation in Mouse Epidermis Is Inhibited by Bromophenacyl Bromide

Phosphorylation of mouse epidermal proteins by endogenous protein kinases and production of arachidonic acid are processes stimulated by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. In mouse epidermal homogenates, each process, as well as production of diacylglycerol (the physiologic activator of protein kinase C), was inhibited by bromophenacyl bromide at concentrations equivalent to those that inhibit tumor promotion. These results lend support to the hypothesis that tumor promotion in mouse skin may be mediated by activation of protein kinase C.