Analysis of the biological results from a complementary DNA (cDNA) microarray using Ingenuity Pathway Analysis (IPA) and the Database for Annotation, Visualization and Integration Discovery (DAVID) revealed protocadherin gamma subfamily A, 9 (PCDHGA9), belonged to protocadherins (Pcdhs), as a potential novel biomarker in GC. Here, PCDHGA9 is linked to gastric cancer.