PECAM1 and acute myeloid leukemia: With a similar approach, Passaro and colleagues92 examined the changes affecting BM stromal cells during AML development using an AML PDX model.92 They showed that major niche components, including CD31+ cells, Col1a1+ cells, and Nestin+ cells, which overlapped with the signature of endothelial, skeletal, and smooth muscle cells, respectively, underwent gene expression changes upon AML engraftment.