SOX2 and colorectal carcinoma: To determine whether CRC growth can be attenuated by modification of the acidic tumor microenvironment and VDR expression, we injected CRC cells into nude mice and gave the mice water or a sodium bicarbonate (NaHCO3) solution.20,21 We found that NaHCO3 treatment after VDR overexpression significantly inhibited SOX2 expression (Supplementary Fig. S3e, f) and tumor development (Fig. 6a) and that NaHCO3 treatment also effectively attenuated SOX2 expression and tumor formation after VDR knockdown (Supplementary Fig. S3e, g; Fig. 6b).