Fig. 1. PGCs of AKT-MER transgenic mice. (A) AKT-MER transgenic mice (right) and littermate control mice (left) at E11.5. As the Akt-Mer cDNA is linked to IRES-EGFP, the transgenic mice can be identified by EGFP fluorescence. (B) Flow cytometry analysis of cells from the gonads of E11.5 AKT-MER mice. Suspensions were stained for the PGC-specific marker SSEA-1. EGFP fluorescence was detected in the majority of the transgenic PGCs. (C) Level of AKT activation in the cultured PGCs. The E11.5 PGCs were seeded onto SCF-expressing Sl/Sl⁴-m220 feeder cells and cultured with or without bFGF and 4OHT for 1 day. The cells were stained with the SSEA-1 (green) and anti-Ser437-phosphorylated-AKT (pAKT) (red) antibodies. The fluorescence intensity of phospho-AKT in the individual PGCs was measured using LSM5 PASCAL confocal microscopy. Relative fluorescence per cell is shown in the right panel (mean±s.e.m.). The background fluorescence level was measured in the samples that were not treated with pAKT antibody. Phospho-AKT signals were stronger in the 4OHT-treated transgenic PGCs than in the untreated transgenic and the bFGF-treated wild-type controls (^*P<0.01, ^#P<0.05, Student's t-test). The signals were stronger in the transgenic PGCs than in the control PGCs, even in the absence of 4OHT and bFGF (^#P<0.05).