Induction of a novel nuclear protein (p54) by phorbol esters in mouse erythroleukemia (Friend) cells.

Tumor-promoting phorbol esters including 12-O-tetradecanoylphorbol-13-acetate (TPA), specific inhibitors for erythroid differentiation in mouse Friend cells, induce a newly identified nuclear protein with a molecular weight of 54,000 (p54) in Friend cells. Phorbol, an analogue of TPA with neither tumor-promoting nor differentiation-inhibitory activity, did not induce p54. In a variant cell line of Friend cells which exhibits resistance to TPA in erythroid differentiation, p54 was not induced by TPA. The induction of p54 by TPA was counteracted by erythroid-inducing agents including dimethyl sulfoxide, hexamethylenebisacetamide, and actinomycin D. Throughout these experiments, we have observed an inverse relationship between p54 induction and cellular potential for erythroid differentiation.