ABCB1 and neoplasm: In recent years, epithelial–mesenchymal transition (EMT) has been shown to be an important factor in the development of drug resistance in tumor cells, and the mechanisms that help tumor cells to develop drug resistance are mainly attributed to overexpression of drug transport proteins (p-glycoprotein, multidrug resistance associated protein 1, etc.)and inhibition of tumor cell apoptosis [89].