CCNB1 and acute lymphoblastic leukemia: To validate RPPA results, we confirmed by immunoblots that 5Z7O induced PARP cleavage, H2AX phosphorylation, and p27 expression in T-ALL cell lines while inhibiting expression of phosphorylated CDK1 (CDC2) and Cyclin B1, both key components of the G2/M checkpoint (Figure 4B).