However, when crossed with the established Eμ-TCL1 CLL-mouse model (Eμ-XPO1/TCL1), concurrent presence of E571K or E571G XPO1 mutations with overexpression of the TCL1 oncogene sufficiently enhanced the rate in which these mice developed their CLL-like phenotype. This evidence concerns the gene XPO1 and B-cell chronic lymphocytic leukemia.