FoxA2 negatively regulates the cell proliferation by blocking the mTOR signal. FoxA2 blocks phosphorylation of p70S6K and S6, and proliferation of the cells without inducing programmed cell death. Plasmids expressing control GFP (A,A’,D,D’,G,G’,J), FoxA2 (B,B’,E,E’,H,H’,K) or FoxA2 together with CA-mTOR (C,C’,F,F’,I,I’,L) were electroporated into one side of the neural tube of HH stage 12 embryos and the phenotypes were analyzed at 48 hpt by immunofluorescence with pHH3 (A–C’), p-p70S6K (D–F’), pS6 (G–I’), and GFP (A’–L’) antibodies. The merged cells of pHH3 (C,C’), p-70S6K (F,F’), or pS6 (I,I’) with GFP expression are indicated by filled arrowheads, and the pHH3- (B,B’), p-p70S6K- (E,E’), and pS6- (H,H’) negative on GFP-positive cells are indicated by outlined arrowheads. (J–L) The cell fate determination for FP by FoxA2 is not altered by CA-mTOR. F-spondin-positive cells were identified by in situ hybridization. The F-spondin expression ectopically induced by FoxA2 is indicated by filled arrowheads (K,L). Analysis in (J–L) were performed on the adjacent sections of (G–I), respectively. (M) Quantitative data for (A–C’). Scale bar = 50 μm. ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001.