Having observed that treatment with 5 μM of CPX significantly induced G1 arrest (Figure 2) and remarkably downregulated the protein level of Cdc25A in tumor cells (Figure 3A), we reasoned that CPX at this concentration might inhibit the activity of CDK2 by increasing the level of its inhibitory phosphorylation, leading to G1 arrest in the cells. Here, CDK2 is linked to neoplasm.