ABCB1 and pancreatic neoplasm: Previous studies demonstrated that nucleoside transporters (NTs) family (ENT1 (SLC29A1), CNT1 (SLC28A1), CNT3 (SLC28A3)), ribonucleotide reductase (RR) family (RRM1, RRM2), excision repair cross-complementation 1 (ERCC1), PLK1, and multiple-drug resistant protein 1 (MRP1, ABCB1) were vital in the metabolic process of gemcitabine in pancreatic cancer cells [3].