Effects of protein kinase inhibitors on growth factor-stimulated DNA synthesis in cultured rat vascular smooth muscle cells.

The effects of H-7 and ML-9, inhibitors of protein kinase C and myosin light-chain kinase, respectively, on DNA synthesis stimulated by platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) were studied in cultured rat vascular smooth muscle cells (VSMC). H-7 and ML-9 significantly inhibited PDGF-stimulated DNA synthesis in lower concentrations, while both compounds were only effective in inhibiting EGF-induced DNA synthesis in higher concentrations. These data suggest that protein kinase C and myosin light-chain kinase activated by PDGF play a more important role in cell proliferation of VSMC than EGF.