Hansdottir et al. [105] also found reduced CYP27B1 expression in lung cancer derived cells compared with primary lung epithelial cells, indicating that the cancer cells did not convert 25(OH)D to 1,25(OH)2D. High CYP24A1 and low CYP27B1 both result in lower levels of 1,25(OH)2D, so, taken together, these studies suggest that low 1,25(OH)2D levels may be important in lung cancer progression. Here, CYP27B1 is linked to lung cancer.