To study the athero‐protective role of CYP27A1 in vivo, Cyp27a1 KO mice were crossed with ApoE KO mice known for their propensity to spontaneously develop atherosclerosis, and the resulting offspring were fed a western diet (WD) for 3 and 6 months 5. The gene discussed is CYP27A1; the disease is atherosclerosis.