A, FACS sorting schema for purification of CD49fhiEpCamlow MMTV-Wnt-1 TIC-enriched cells. B–D, VDR functional responses in breast cancer TICs. Sorted CD49fhiEpCamlow TIC cells were treated with 1 nM calcitriol (Cal) for 16 h and mRNA levels of Vdr, Cyp24, and Cyp27b1 were determined by qRT-PCR (n = 3; *** p<0.01 as compared to the CON group; ND, not detected). Values represent mean ± SEM.