Effect of fluphenazine on the stimulation of calcium-sensitive phospholipid-dependent protein kinase by 12-O-tetradecanoyl phorbol-13-acetate.
The addition of the tumor-promoting phorbol ester 12-O-tetradecanoyl phorbol-13-acetate resulted in activation of calcium-sensitive phospholipid-dependent protein kinase which was dependent on the presence of phospholipid but was essentially independent of calcium. Fluphenazine, which is an effective inhibitor of the ability of this phorbol ester to stimulate proliferation in calcium-deprived non-neoplastic cells, inhibited the enzyme in the absence or presence of the phorbol ester (Ki = 16 microM). Fluphenazine inhibition was competitive with phospholipid but non-competitive with 12-O-tetradecanoyl phorbol-13-acetate.