CBFβ-SMMHC expression inhibits human HSPC differentiation and negatively affects progenitor cell activity. (A) Human CD34⁺ cells were transduced and sorted for GFP expression. On the day of sorting, GFP⁺ cells were analyzed by flow cytometry for the indicated surface markers. (B) Two thousand GFP⁺ cells were plated in serum-free methylcellulose culture. Total colony numbers were scored after 14 days. Average total colonies (top) or frequency (bottom) are shown with SDs for a representative experiment. ^*P < .05. (C) After expansion of GFP⁺ cells for 3 days, apoptosis and cell cycle analysis by annexin V staining and BrdU incorporation, respectively.