NTRK1 and synovial sarcoma: Gene expression profile comparison of SS to other sarcoma types has helped identify a handful of genes that are preferentially associated with SS [22]–[24] and suggests the implication of several signaling pathways in SS pathogenesis, including receptor tyrosine kinases, Hedgehog, Notch, RAR, TGFβ and Wnt [25]–[29].