ABCG2 and cancer: Results showed that, in ESCC cells with exogenous knockdown of RIT1, multiple drug-resistant transporter gene ABCG2, stemness-associated gene Smo and ALDH1, and cancer stem cell-related surface marker CD105 and CXCR4 were significantly upregulated (Fig. 6c), whereas in cells with exogenous overexpression of RIT1, multiple drug-resistant transporter gene ABCG2, stemness associated genes OCT4, smo, and ALDH1, as well as stem cell-related surface markers CD44, CD105, CD166, and CXCR4 were significantly downregulated (Fig. 6d).