S100A9 and synovial sarcoma: From an initial selection of 35 candidate genes, 14 feature genes were ultimately identified as potential biomarkers for SS: MAPK3, NAT1, CXCL10, IL15, PRDX4, BIRC3, EZH2, SKI, MAD2L1, ATP2A3, HMGA1, BST2, IFI27, and S100A9. Apart from ATP2A3, HMGA1, MAPK3, and SKI, the remaining genes exhibited elevated expression predominantly in SS patients.