Protein kinase C activities and bindings of a phorbol ester tumor promoter in 41 cell lines.

The activities of protein kinase C (PKC) and the bindings to phorbol-12,13-dibutyrate (PDBu) of 41 cell lines were measured. The activities of PKC varied from 0.2 to 37 mU/10(6) cells in different cell lines, and in general were high in normal or untransformed cells and low in malignant, or transformed cells. The PDBu binding also varied considerably in different cell lines, and was again higher in normal or untransformed cells. In some cell lines, the binding was much higher at 4 degrees C than at 37 degrees C, suggesting rapid down-regulation of the binding. A correlation between PKC activity and PDBu binding was found only within certain cell types, i.e., epithelial cell lines derived from human tumors.