Phorbol ester activation of epidermal protein kinase C from tumor promotion sensitive and resistant mouse strains.

Calcium-stimulated, phospholipid dependent protein kinase C activity was found in cytosolic extracts of the epidermis of SENCAR, C57BL/6 and Ha/ICR mice. The enzymes were partially purified by DEAE-cellulose chromatography. There were no significant differences between the 3 strains in basal protein kinase C activity. The enzymes from all 3 strains were stimulated by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in the absence of calcium, but no correlation was seen between susceptibility to tumor promotion and any protein kinase C activity parameter measured.