CD274 and gastric cancer: In the course of studies on other types of tumors, ubiquitinating and deubiquitinating enzymes have been found to regulate PD-L1 expression, for example, the deubiquitinating enzyme USP7 removes PD-L1 ubiquitination in gastric cancer cells70 and stabilizes PD-L1; the E3 ligase FBXO22 ubiquitinates and proteasomal degrades PD-L1.71