VDR and colonic neoplasm: While it was long held that vitamin D acted only at the intestine, kidney, and skeleton, and that its function was limited to calcium homeostasis, the possibility of extraskeletal effects has been considered for decades as a result of the discovery of the VDR in tissues that have no involvement in calcium homeostasis (e.g., skin, placenta, pancreas, breast, prostate and colon cancer cells, and activated T cells).