Ligand-controlled proliferation, survival, and differentiation of cCLPs. FACS-purified Lin⁻Flk2⁺IL7R⁺CD27⁺Ly6d⁻ cells from 1-month cCLPs were further cultured for another 7 days, starting from 1 × 10⁴ cells on 24-well flat-bottom plates at day 0 (this number of cells at the start of the cultures is indicated by an arrow), in various combinations with OP9, Flt3L (25 ng/mL), IL-7 (0.1 ng/mL), immobilized kitL (imkitL, 1 μg/mL), CXCL12 (100 ng/mL), FBS (2%), anti-ckit monoclonal antibody (10 μg/mL), and/or AMD3100 (10 μM). Statistical analysis of numbers of CD27⁺CD19⁻ (logarithmic scale, left panel) and CD27⁻CD19⁺ cells (linear scale, right panel) are shown. On the left panel, cell numbers in culture at day 7 <10⁴ (ie, decreased numbers within these 7 days), are drawn in blue whereas those >10⁴ are drawn in red, indicating increased numbers within 7 days. Error bars indicate mean (n = 3) ± standard deviation. **P < .01. These data are representative of 3 independent experiments.