KDR and acute myeloid leukemia: Excitingly, time-lapse studies of the BM calvarium captured the formation of Flk1-GFP+ EVs in AML-burdened mice, where EVs were released as a result of direct budding from the endothelium or occasionally, by complete endothelial cell fragmentation (Fig. 5c, e, f; Supplementary Videos 13–14).