Fig. 5. Inhibition of neurogenesis by STAT3 in a non-cell-autonomous manner. (A,B) NPC cultures were prepared from the neocortex of E12.5 STAT3^flox/flox mice and infected with a retrovirus encoding GFP (pMX-GFP). Neuroepithelial cell cultures were prepared from STAT3^flox/flox embryos and infected with retroviruses encoding CD8 alone (Control) or both CD8 and Cre recombinase (Cre). The infected NPCs (1x10⁵ cells) were co-cultured for 4 days in the presence of low dose FGF2 (2 ng/ml) with the infected neuroepithelial cells (1x10³ cells) and stained with anti-GFP and anti-CD8 (A), or anti-GFP and TuJ1 antibody (B). (A) GFP and TuJ1 fluorescence merged image are shown for typical field of co-culture experiments. Scale bar: 80 µm. (B) The percentage of clones containing only TuJ1-positive cells among GFP-positive clones was then determined by immunocytofluorescence analysis. ^*P<0.01. (C) NPC cultures prepared from the neocortex of E12.5 wild-type mice were infected with pMX-GFP and co-cultured with neuroepithelial cell cultures infected with pMX-CD8 (Control) or a retrovirus encoding both CD8 and STAT3-C (STAT3-C) as in B. ^*P<0.05.