To examine the protein expression levels of the four genes (APOB, VCAN, ABCA6, and CTSF) in gastric cancer, we performed immunohistochemistry (IHC) on the pathological section of the samples from patients of different stages, including normal, paracancerous tissue, early gastric cancer (EGC), and advanced gastric cancer (AGC) (Figure S16B–D). Here, APOB is linked to gastric cancer.