Impaired self-renewal and differentiation of RapGEF2^−/− hematopoietic progenitors in vitro. The number of BFU-E, CFU-Mix, and CFU-GM colonies formed from RapGEF2^+/+ and RapGEF2^−/− E10.5 yolk sac cells (A-C) or embryonic cells (D-F). The average and standard deviation were derived from 3 independent colony-formation assays. (G-H) Representative photographs showing the size of the CFU-GM colonies derived from RapGEF2^+/+ (G) and RapGEF2^−/− (H) E10.5 yolk sac cells. (I-J) Histograms showing the number of colonies formed in the initial plating 0′ and the subsequent replating i to iii of E10.5 yolk sac (I) or embryonic (J) cells. The average, standard deviation, and statistical significance were derived from 3 independent assays. *P < .05, **P < .005, ***P < .0005. (K-L) Flow cytometry images showing the distribution of CD71⁺Ter119⁺ (K) and Gr1⁺/Mac1⁺ (L) cell populations. (M-N) Bar graphs displaying the number of BFU-E, CFU-GM, and CFU-Mix colonies formed after plating FACS-sorted c-Kit⁺/CD34⁺ double-positive HPCs from E10.5 yolk sac (M) or embryonic cells (N). Compared with RapGEF2^+/+, 5 times more number of RapGEF2^−/− yolk sacs and embryos were pooled to obtain sufficient number of c-Kit⁺/CD34⁺ HPCs.