Here, we showed that the apoptotic factors PARP1 and CASP3 are abnormally activated in Tcl1-/- KCs with respect to WT and the K14-TCL1 expression is sufficient to restore physiologic activation levels, resembling the TCL1 anti-apoptotic effect observed in human CLL [25]. Here, CASP3 is linked to B-cell chronic lymphocytic leukemia.