Fig. 2. Endoglin marks the blast colony-forming cell. (A) A representative FACS profile of a time-course analysis for endoglin and FLK-1 expression in Eng^+/+ and Eng^-/- ES cells (day 0, d0) and EBs differentiated for 2, 3, 4 and 6 days. Fluorescence intensity for endoglin is indicated on the y axis and for FLK-1 on the x axis. (B) Gene expression analysis of Eng^+/+, Eng^+/- and Eng^-/- ES cells during EB differentiation. (C) Wild-type day 3 EBs were sorted based on expression of endoglin and FLK-1, according to represented gates, as follows: ENG⁺FLK-1⁺, ENG⁺FLK-1^-, ENG^-FLK-1⁺ and ENG^-FLK-1^-. Resulting cell fractions were plated immediately for blast colonies (BL-CFCs). Error bars indicate standard deviations from two independent experiments performed in duplicate. ^*, P<0.05 versus the other three cell fractions.