Some cancer studies have preliminarily explored the role of PTGR1 in regulating the cell cycle and resisting oxidative stress.51,52 Decreased PTGR1 expression in DU145 and PC3 cells induced G0/G1-phases arrest, which was related to the increased protein levels of p21, Caspase 3, and cleaved PARP, as well as the decreased expression of CCND1.52 Interestingly, metformin has been well recognized as an antiproliferative agent that induces cell cycle arrest. The gene discussed is CCND1; the disease is cancer.