CDKN2A and breast cancer: Artemisinin induced a strong stringent G1 cell cycle arrest in prostate cancer cells, human breast cancer cells and nasopharyngeal cancer cells by down-regulating the expression of CDK2, CDK4, cyclin E, cyclin D1 and E2F1, and increasing the expression of p16 (also known as cyclin-dependent kinase inhibitor 2A) [36].