CD200 and gastric cancer: An immune checkpoint correlation analysis demonstrated that GSDME was closely associated with immune checkpoints TNFSF9, TNFSF15, TNFSF18, TNFSF4, TNFRSF25, TNFRSF4, TNFRSF8, LGALS9, NRP1, CD276, CD40, and CD200 in gastric cancer.