VDR and breast cancer: The main results of the present study are as follows: (1) the transcriptional repression of KCa1.1 by the treatment of human breast cancer MDA-MB-453 cells with VDR agonists (see Figure 3); and (2) the promotion of KCa1.1 protein degradation by the treatment with VDR agonists in MDA-MB-453 cells (see Figure 5).