Prolonged and enhanced production of myeloid progenitors by cyclin D2–overexpressing LSK cells. (A) Control- or cyclin D2–transduced LSK cells were cultured in SFM and, at the time points indicated, plated into methylcellulose, and 7 days later evaluated for colony formation. The number of GFP⁺ colonies generated from day 0 (after transduction) was set as 100% and compared with colony formation at later time points. (B) Control- or cyclin D2–transduced LSK cells were plated in methylcellulose cultures, and colonies were scored after 7 and 11 days. Results are shown as number of GFP⁺ (or GFP^–) colonies at day 11/number of day-7 colonies × 100. Transduction efficiency was 80% (67%-86%) and 50% (42%-55%) (A), and 73% (67%-78%) and 43% (40%-51%) (B) for control- and cyclin D2–transduced colonies, respectively. Data are mean (SD) values from 3 (A) and 4 (B) experiments. * P < .05.