PDCD1LG2 and gastric cancer: Concerning intrinsic functions, PD-L2 has been less studied in cell lines, whereas PD-L1 has been implicated in resistance to chemo- and radiotherapy in the MDA-MB-231 cell line [30] and apoptosis, as well as induction of cell proliferation, migration, and invasion processes in gastric cancer and pancreatic carcinoma cell lines [25].