CYP24A1 and breast carcinoma: This study demonstrated the presence of an IRES element within the 5'UTR of CYP24A1 mRNA that was activated by the inflammatory milieu in a PI3K‐dependent manner, potentially linking a common oncogenic pathway in human breast cancer (AKT‐PI3K) with activation of vitamin D catabolism.(14) Although these and other studies have identified several mechanistic pathways that alter vitamin D metabolism in vitro, additional factors likely contribute to deregulation of vitamin D metabolic enzymes in human breast tumors as discussed below.