Notably, the progressive accumulation of CLL-like B cells in Eμ-MTCP1 mice followed a similar trend to that observed in Eμ-TCL1 mice (Supplementary Fig. 3A)—a widely used CLL mouse model which reliably (reported 95–100% penetrance) develops a CLL-like phenotype driven by overexpression of recombinant human TCL1A also under control of a VH promoter-IgH-Eμ enhancer31,32. Here, MTCP1 is linked to B-cell chronic lymphocytic leukemia.