Gene expression in hematopoietic progenitors. Gene expression in sorted hematopoietic populations from wild-type and DKO ES cells, as described in supplemental Figure 2, was measured by real-time PCR. Gene expression was normalized to Gapdh and levels in wild-type CMPs was set to 100%. Experiments were performed 3-5 times and error bars indicate the standard deviation. We tested expression of genes coding for GATA1, VWF, FOG1, GATA2, MPO, C/EBPα, PU.1, and G-CSF-R. Difference in expression between paired hematopoietic populations from wild-type and DKO ES cells was significant at **P < .005 or *P < .05.