Figure 6

FGF1 phosphorylation inhibits its anti-apoptotic activity. (a and b) Neo, FGF1^WT, FGF1^S130A and FGF1^S130D PC12 cell lines were treated with dexamethasone for 48 h. p53-dependent apoptosis was then induced by etoposide treatment during 40 h. (a) Cell survival was estimated by crystal violet nuclei staining (**P<0.01, ***P<0.001, ns P>0.05, n=6). (b) Apoptosis (percentage of apoptotic nuclei) was estimated after Hoechst nuclei staining (*P<0.05, **P<0.01, ns P>0.05, n=3). FGF1^WT and FGF1^S130A protected PC12 cells from p53-dependent apoptosis in contrast to FGF1^S130D. (c) Neo, FGF1^WT, FGF1^S130A and FGF1^S130D PC12 cells cultured in the presence of dexamethasone were treated with etoposide for 0, 8 or 16 h. The levels of P-p53 (Ser 15), PUMA and cleaved caspase-3 were detected by western blot. Actin was used as a loading control. FGF1^WT, FGF1^S130A and FGF1^S130D decreased etoposide-induced upregulation of these different apoptotic markers. The stronger effect was observed for the unphosphorylable FGF1