Fig. 4. FLK1⁺CD4⁺ cells from D2.75 EBs are enriched for the hemangioblasts. (A) FLK1⁺CD4⁺, FLK1⁺CD4^- and FLK1^-CD4^- cells were FACS-sorted and subjected to blast colony replating (6x10⁴ cells/ml). The resulting blast colonies were counted 4 days later. Secondary EBs were also counted and shown. Error bars indicate standard deviations from triplicate plates. (B) Gene expression analysis. RNA from FLK1⁺CD4⁺, FLK1⁺CD4^- and FLK1^-CD4^- cells were amplified and probed with Flk1, Scl, Gata1, Gata2, Lmo2 and L32. 1, unsorted 2.75 EBs; 2, FLK1⁺CD4⁺; 3, FLK1⁺CD4^-; 4, FLK1^-CD4^-; 5, water — a negative control for RT-PCR.