Knockdown of circPVT1 decreased the expression level of a well-known drug transporter gene, ABCB1. From previous discoveries, it was found that the gene promotes chemoresistance via removing the intracellular drugs by P-glycoprotein (P-GP) an ATP-dependent efflux pump that may have to metabolize the drugs in cancer cells (Callaghan et al., 2014). The gene discussed is ABCB1; the disease is cancer.