ABCB1 and cancer: The cytotoxic potency of pLAn-SS-CTX NPs was also assessed in two paclitaxel-resistant cancer cell lines (i.e., A549/PTX and HeLa/PTX cells), both of which were characterized by high levels of P-glycoprotein (P-gp, encoded by ABCB1 gene) using western blot analysis (Figure 4E).