TAL1 is required for the development of human myeloid committed progenitors. Transduced CD34⁺ cells were plated in methylcellulose culture and in myeloid differentiation in liquid culture. (A) GFP⁺ and GFP^– colonies from BFU-Es and GM-CFU cells 14 days later. (B) TAL1 and LYL1 expression during myeloid differentiation detected by real-time quantitative PCR; dashed line indicates the arbitrary 100% of TAL1 expression determined in shRNActrl cells at day 0 of the culture. Shown is the mean of 2 measurements. (C) Analysis of CD15 and CD34 marker expression after 10 days of culture in both GFP^– and GFP⁺ cells (one representative experiment, 10 days). (D) Evolution of GFP⁺/CD15⁺ cell numbers during the culture. Data are expressed as the mean plus or minus the standard error (SE) of 2 to 5 independent experiments.