VDR and breast cancer: Assessing the effect of high dose VD on the following biomarkers in the BC cells: VDR, estrogen receptor (ER), progesterone receptor (PR), epidermal growth factor receptor 2 (Her2/neu), androgen receptor (AR), as well as epidermal growth factor receptor 1 (EGFR) and Ki-67, as markers of proliferation, and E-cadherin, a marker of invasion and metastasis.