ABCB1 and neoplasm: Tumor volume of mice treated with paclitaxel alone was approximately 3-fold higher than in mice treated with combined HA-PEI/HA-PEG/MDR1 siRNA CD44 targeted nanopartricle and paclitaxel, which could reflect an increased chemosensitivity to paclitaxel in mice treated with HA-PEI/HA-PEG/MDR1 siRNA.