It is responsible for phosphorylation of PBK (downregulated) during mitosis which is required for its mitotic activity.[74] In addition to its role in cytokinesis during mitosis, overexpressed PBK is found in numerous cancers such as colorectal cancer,[75] bladder cancer,[76] and gastric cancer.[77] In addition to CCNB1, CDK1 is linked to other genes involved in cell cycle regulation in the network, such as TOP2A, SPC25, NDC80 kinetochore complex component (SPC25), CDKN3, KIF4A, TTK, CDKN2C, and TPX2 (all downregulated), and tankyrase 1 binding protein 1 (TNKS1BP1) (upregulated). This evidence concerns the gene TOP2A and cancer.