Knockdown of BMI1 reduces cell growth and CFC formation in liquid culture conditions. (A) CB CD34⁺ cells were transduced with control (scrambled) scr-RNAi or BMI1-RNAi particles, sorted, and plated in stroma-free liquid conditions (IMDM supplemented with 10% FCS, 10 ng/mL IL-3, and 100 ng/mL TPO). Cumulative expansion is shown of a representative experiment of 3 independent experiments. (B) Progenitor content was determined by CFC assays in methylcellulose at week 2 of liquid culture. CFCs per 10 000 cells (left panel) as well as the total amount of generated CFCs (right panel) are shown. (C) Representative micrographs of colonies in methylcellulose displaying a reduction in colony size after BMI1 knockdown in cells from week 2 liquid cultures. (D) Hematopoietic differentiation was analyzed by FACS on suspension cells from MS5 cocultures at week 1.