CYP27A1 and Hypercholesterolemia: In the context of HCD induced hypercholesterolemia, pulmonary CYP27A1 expression increased in the HCD fed mice compared to the ND fed mice (Fig. 4A), suggesting a highly possibility that CYP27A1 mediated pulmonary cholesterol efflux might provide considerable amounts of metabolites for the activation of LXRs.