The cytotoxic effect of chemotherapy is overcome through several mechanisms, including enhanced ABC transporters, facilitated ALDH activity, and overexpressed B-cell lymphoma-2 (BCL2) [52].Exposure to doxo leads to increased multi drug resistance (MDR) phenotype in cancer cells, with cross-resistance to chemotherapeutic agents correlating with overexpressed P-gp [53, 54]. Here, ABCG2 is linked to cancer.