PYM1 and tongue cancer: Moreover, CA9 knockdown markedly impaired ZEB1-mediated drug resistance to PYM or cDDP in Tca8113 and SCC-25 cells (Figure 2A and B), while overexpression of CA9 in Tca8113/PYM cells impaired the effect of ZEB1 knockdown in response to chemotherapy (Figure 2C), suggesting CA9 is responsible for ZEB1-mediated drug resistance in tongue cancer cells.