Enforced expression of Arid3a also augmented the capacity of the TCL1 Tg to promote B CLL/lymphoma, including those expressing the VH12+ aPtC BCR as previously found among the B1a cell-derived B CLL/lymphoma in TCL1 Tg+ mice (7) (Figure 4F). Here, BCR is linked to B-cell chronic lymphocytic leukemia.