Immunofluorescence analysis for OCT4 (red), BLIMP1 (green), and T (white) on days 0, 1, and 2. Nuclei were stained with Hoechst (blue). The culture contained BMP4 (5 ng/ml), Activin A (50 ng/ml), and bFGF (20 ng/ml). Scale bar: 100 μm. 