At the functional level, we show here that not only the cellular levels of μ-calpain strongly correlate with spontaneous apoptosis of the blasts (Fig 6), but also it is possible to significantly (on average more than twofold) increase the rate of ALL blast apoptosis in vitro by treatment with membrane-penetrating calpain inhibitor (Fig 7). This evidence concerns the gene CAPN2 and acute lymphoblastic leukemia.