Since PC-PLC inhibition had substantial effects on A431-AD squamous cancer cell proliferation, we investigated the changes induced by D609 (50 μg/ml) on the phosphorylation level of EGFR, as well as on the phosphorylation of ERK1/2 and AKT, in order to elucidate whether the inhibitor could interfere with the activation of the two major signaling pathways responsible for cell growth and survival. The gene discussed is MAPK3; the disease is Alzheimer disease.