Moreover, in a mouse model of pancreatic cancer, lactate, a product of glycolysis, was shown to activate MDSCs via the G protein-coupled receptor 81 (GPR81)/mTOR-HIF-1α/signal transducer and activator of STAT3 pathway [60]; this study simultaneously refreshed the understanding of radiation therapy for pancreatic cancer. This evidence concerns the gene HCAR1 and familial pancreatic carcinoma.