BCR and leukemia: Our comparative analysis between stage-defining gene expression in wild-type progenitor B cells and different human B-ALL subtypes suggests that cycling pro-B, pre-BCR-dependent, and preBCR-independent subsets shared the highest similarities with high-risk human B-ALL subsets, including BCL2/MYC, IKZF1 N159Y, and KMT2A-rearranged leukemias.