CDK4 and central nervous system cancer: Our groups previously reported that tigecycline affected cell cycle progression in multiple malignant tumours, including melanoma,20 glioma,22 neuroblastoma 21 and oral squamous cell carcinoma.19 Consistently, tigecycline was also shown to be responsible for G0/G1 cell cycle arrest in PDAC cells by down‐regulating the expressions of Cyclin E2, CDK2 and CDK4.