Effects of Notch activation on colony-forming ability of primary hematopoietic progenitors. (A) CD34⁺ MSCV-GFP and MSCV-ICN/GFP cells were grown in liquid culture in presence of cytokines. After 2 weeks, cells were obtained and plated in triplicate, at a density of 10,000 cells/mL in methylcellulose supplemented with IL-3, KL, and EPO. Columns represent the average of three experiments. CFC are expressed per 10,000 cells. Error bars represent standard deviation. Difference between the two populations is statistically significant (P = .033). (B) CD34⁺cocultivated with 3T3pBABE or 3T3pBABE-J2 were obtained and plated in triplicate at the density of 1,000 cells/mL in methylcellulose, as described above. Columns represent fold increase in colony formation by progenitors exposed to Jagged2 versus control in two experiments. CFU-mix included at least two myeloid lineages and erythroid cells as assessed by phase microscopy. Error bars represent standard deviation. *, P = .046; **, P < .03.