Cyclin D1 down‐regulation also results in inhibition of cell cycle progression and cell cycle arrest in proliferating cancer cells; nevertheless, it was postulated that its down‐regulation by iron depletion is mediated by other than RR activity–related mechanisms,8, 42 likely involving PHDs from the iron and 2‐OG‐dependent dioxygenase family.12, 13. Here, CCND1 is linked to cancer.