VDR and breast cancer: These observations are consistent with a recent report that low VDR protein expression in clinical breast cancer specimens is associated with higher tumor grade and more aggressive tumor types.(23) In this data set, tumors from the VDR Low subgroup also exhibited unique genomic alterations, being less likely to contain PI3KCA mutations and more likely to exhibit copy number alterations (CNAs) in CCDN1 (encodes Cyclin D1) and three fibroblast growth factor genes (FGF3, FGF4, FGF19) than the VDR Normal subgroup (Fig. 2E).