CD5 and mantle cell lymphoma: Breeding Cdk4R24C mice (a knock-in strain expressing a Cdk4 resistant to p16INK4a inhibition and other Ink4 family members [23]) with c-myc-3’RR mice (that developed aggressive BL) led to the development of clonal indolent blastoid MCL-like lymphoma (CD19+IgM+CD5+CD43+CD23- cells) in c-myc-3’RR/Cdk4R24C mice [24].