Protein kinase C in human pheochromocytoma

Subtypes of protein kinase C were analyzed in adrenal and extra-adrenal pheochromocytoma of humans. Almost all protein kinase C of the adrenal tumor was type III, while the enzyme of the extra-adrenal tumor was separated into two major fractions corresponding to type II and type III by hydroxyapatite column chromatography. The extra-adrenal tumor but not the adrenal tumor spontaneously produced neurite-like processes when the cells were cultured in vitro. These results suggest that the high proportion of type II enzyme may reflect neuron-directed differentiation in human pheochromocytoma.