We also observed that the expression of BMPR1A was significantly correlated with that of Id1 in AML samples (P = 0.0017) (Fig. 2b) and that after sorting MNCs according to their membrane-BMPR1A content (Fig. S3a), we observed a higher Id1 expression in BMPR1A+ cells (Fig. S3b). Here, ID1 is linked to acute myeloid leukemia.