SOX2 and colorectal carcinoma: Moreover, we found that the active form of vitamin D could reverse the acidic environment-mediated promotion of self-renewal and CD133, SOX2, and OCT4 expression in CRC stem cells (Fig. 4i, j; Supplementary Figs. S2e and 4k), suggesting that the acidic microenvironment affects the stemness of CRC cells through the vitamin D-VDR signaling pathway.