Control of ribosomal protein phosphorylation in HeLa cells

The effects of a large series of hormones, cyclic nucleotides and metabolic inhibitors on phosphorylation of ribosomal protein S6 in HeLa cells suggest that at least two metabolic pathways are involved. One responds to insulin and epidermal growth factor; the other responds to adenosine 3′, 5′-cyclic monophosphate. Some phosphodiesterase inhibitors can suppress the phosphorylation of S6 that ordinarily is stimulated by insulin.