CD44 and colorectal carcinoma: In order to clarify how VDR affects the CSC phenotype and drug resistance in CRC, we used chromatin immunoprecipitation (ChIP) to analyze the regulatory effects of VDR on the transcription of stemness markers and found that VDR could bind to the promoter regions of SOX2, OCT4, CD44, and NANOG (Fig. 3a, b).