Moreover, conditional RNAi-mediated depletion of CHK1 in BL2 Burkitt lymphoma and Nalm6 pre-B ALL cells coincided with the induction of apoptosis, as indicated by PARP1 cleavage, a marker of caspase activation (Supplementary Fig. 1B). The gene discussed is PARP1; the disease is acute lymphoblastic leukemia.