Fig. 1. IGF-I stimulates Akt-phosphorylation in cultured OB neural stem cells. OBSCs derived from E14.5 embryos were treated with 100 ng/ml IGF-I or with BSA for 30 minutes in conditions of proliferation (presence of EGF and FGF-2) and differentiation (in the absence of mitogens). After lysing the cultured cells, proteins were analysed by immunoblotting with specific antibodies against P-Akt^Ser473, P-Akt^Thr308, Akt, P-Erk1/2 and Erk1/2. The very low basal levels of P-Akt were markedly increased by the presence of IGF-I and maintained for up to 24 hours (not shown). Similar results were obtained in samples from six experiments.