VDR and cancer: The NRs associated with cancers include the retinoic acid receptors (RARs) [39,40,41], the retinoid X receptors (RXRs) [41,42,43], the peroxisome-proliferator-activated receptor γ (PPARγ) [43,44,45,46], and the vitamin D receptor (VDR) [47,48,49,50,51].