FGFR2 and synovial sarcoma: Expression of the SS18-SSX2 fusion, which molecularly characterises SS, results in transcriptional upregulation of FGFR2 and increased expression of FGF ligands, FGF3, FGF7, FGF9 and FGF18, suggesting possible autocrine feedback loops function to upregulate FGFR signalling [91].