Protein kinase C activation in a 3T3 cell variant morphologically unresponsive to tumor-promoting phorbol esters

To investigate the mechanism of the morphological changes induced in cells by tumor-promoting phorbol esters, we isolated a 3T3 cell variant which was morphologically unresponsive to phorbol esters and analyzed the activation of protein kinase C induced by the phorbol esters in it. The variant resembled the parent cells in its activation and appeared to have been altered at some step distal to the early events of protein kinase C activation.