Regarding IGF‐1, except anti‐mitogenic and anti‐apoptotic effects of vitamin D treatment on IGF‐1 levels in breast cancer cell line, vitamin D analogue EB1089 has been shown to inhibit the aromatase gene expression in breast cancer cells, via a VDR/Williams syndrome transcription factor (WSTF)‐mediated mechanism.71 The gene discussed is CYP19A1; the disease is breast cancer.