MTHFD1L and familial pancreatic carcinoma: Many previous studies have identified many targets and markers of drug resistance in pancreatic cancer [41–43], but in our research, through multiple verifications, combined with data including bioinformatics, cell experiments, animal experiments, and clinical sample data, we have obtained more reliable results than before, proving that the new circ-MTHFD1L plays an extremely important role in the chemotherapy resistance process of pancreatic cancer through the miR-615-3p/RPN6 axis.