On the contrary, when expressed in a malignant B cell context, RAS-MAPK genetic aberrations accelerate and sharpen the phenotype, as observed for Nras Q61R expression in the Vκ*MYC MM mouse model and Braf V600E expression in the Eμ-TCL1 CLL mouse model. This evidence concerns the gene BRAF and B-cell chronic lymphocytic leukemia.