Hematopoietic colony assays from total yolk sac cells of CBP homozygous mutant embryos and wild-type littermates at E9.5. Numbers of hematopoietic colonies were scored after 7 days of culture of yolk sac cells. Total numbers of colonies (>40 cells) per one yolk sac were obtained from three independent experiments and expressed as the mean ± SEM (n = 3). Methylcellulose culture was performed in the presence of IL-3 (200 U/mL), SCF (50 ng/mL), and Epo (2 U/mL).