ABCB1 and cancer: Multiple research findings have reported the involvement of two molecular “efflux pumps” namely P-glycoprotein (P-gp) and multidrug resistance associated protein (MRP) in tumor cell membrane, that are often responsible for MDR phenomenon in cancer cells by effluxing out the therapeutic agents from the cell (Kartal-Yandim et al., 2016; Ren et al., 2016).