KLK6 and gastric cancer: Alongside the molecules mentioned above, existing studies (see Table P in S1 Text) have reported that CD9, KLK6, HLA-B, MUC1, MET, hsa-mir-7–2, hsa-mir-944, hsa-mir-942, hsa-mir-219a-2, and hsa-mir-1305 also play an important role in the occurrence, progression, or diagnosis and treatment of GC.