FGF18 and synovial sarcoma: Stimulation of human synovial sarcoma cell line HS-SY-II with recombinant FGF18 protein increased the dependence of the cells on FGF18 and enhanced the phosphorylation levels of ERK, P38 and FGFR3 proteins in human synovial sarcoma cell line HS-SY-II.