CCND1 and neoplasm: In prostate cancer cells, metformin activates the 5’ adenosine monophosphate-activated protein kinase, blocks cell cycle in G0/G1 by reducing cyclin D1, inhibits the signaling of mammalian target of rapamycin complex 1, blocks androgen receptor, inhibits tumor-associated inflammatory infiltration, inhibits the signaling pathway of insulin-like growth factor 1, downregulates c-myc oncogene and targets cellular senescence etc. (Tseng, 2022).