In conclusion, our results show that poziotinib reverses MDR in ABCG2- and ABCB1-overexpressing colon cancer cells to their corresponding anticancer drug substrates, It is likely that poziotinib reverses MDR in ABCG2-overexpressing cells by inhibiting the efflux activity of the ABCG2 transporter, as well as by downregulating the expression level of the ABCG2 transporter protein. Here, ABCG2 is linked to malignant colon neoplasm.