We found all three to be adhesive to AML cells to variable degrees (Supplementary Figure S1), with different expression levels of common adhesion markers (Supplementary Table S4, e.g., HUVECs are 100% CXCR4 positive, whereas HS5s do not express CXCR4), highlighting the importance of using a multicellular system. This evidence concerns the gene CXCR4 and acute myeloid leukemia.