Different factors cause MDR like overexpression of ABC transporter especially P-gp, mutations [5], DNA damage and resistance to former chemotherapy drug due to clonal evolution, tumor heterogeneity [6], presence of cancer stem cell-like cells [7], dormancy [8], hypoxia [9], immune evasion [10], horizontally gene/material transfer [11], and tumor microenvironment complexity [12], among others. Here, PGP is linked to cancer.