We generated several independent B-ALL cell lines from the BM of wild-type (WT, n=10) and major histocompatibility complex 1 (MHC-I)-deficient mice (B2m-/-, n=10) and characterised their surface expression of ligands for NK-cell receptors and susceptibility to NK cell–mediated killing. The gene discussed is B2M; the disease is acute lymphoblastic leukemia.