In addition, genetic or drug-induced inactivation of BcR signaling in tcl1 mice causes a substantial delay in the onset of leukemia [238], whereas a more efficient BcR signaling, obtained via genetic inactivation of the PTEN molecule, which has a negative regulatory effect on BcR signaling, results in an accelerated onset of leukemia [239]. The gene discussed is PTEN; the disease is leukemia.