Early kinase C dependent events in aging human diploid fibroblasts

Two early kinase C dependent events, the induction of c-fos transcription and the phosphorylation of an 87 kDa protein, were investigated in aging IMR 90 human diploid fibroblasts. C-fos induction and 87-kDa protein phosphorylation were similarly regulated in aging cells and their young counterparts. The data suggests that G0 exit or the competence phenomenon is intact in aging cells and that the proliferative block occurs later in G0/S.