Fig. 8. VEGF induces SCL-expressing cells mainly through the FLK1 receptor. (A) Wild-type, Flk1^–/– and Flt1^–/– ES clones were differentiated in serum or serum-free conditions, in the presence of BMP4 and VEGF as shown. Day 5-6 EBs were analyzed for CD31 and TER119 expression. The percentage of TER119 and CD31-positive cells are shown. One representative experiment out of three is shown. (B) Flk1^–/– and Flt1^–/– EB cells generated in the presence of FCS (black bar), SR+BMP4 (white bar), or SR+BMP4+VEGF (grey bar) were re-plated in a semi-solid medium as described in the Materials and methods. Hematopoietic colonies were counted 5-7 days after re-plating. No hematopoietic colonies formed when EB cells from SR were re-plated, thus not shown. Error bars indicate standard deviations from triplicate plating. One representative experiment out of three is shown.