CDK5 and cancer: CDK5 has unignorable role in tumor progression and metastasis in numerous cancers, including head and neck squamous cell carcinomas, hepatocellular carcinoma, prostate cancer, medullary thyroid carcinoma, ovarian cancer, and chemotherapy-resistant cervical tumors of the uterine cervix and the bladder [12,13,14,15,16,17,18,19,20,21].