SOX2 and colorectal carcinoma: Compared with a pH of 7.4, a pH of 6.8 significantly increased the percentage of CD133-positive cells and promoted the expression of the stemness markers prominin 1 (CD133), POU class 5 homeobox 1 (OCT4) and SOX2 in non-stem CRC cells (Fig. 1c; Supplementary S1e, f).