Fig. 7. The progression of cells from being OLIG2-positive to NG2-positive requires both MAPK and PI 3-kinase activation. Neocortical cells were initially cultured in the presence or absence of SHHAg or FGF2 for 48 hours until OLIG2-positive cells appeared. The inducers were then removed and the medium replaced with defined medium containing U0126 or LY294002. The appearance of NG2-positive cells in the cultures was inhibited by both drugs.