In this extensive screening, these authors identified Axl, EphB2, FGFR2, IGF-1R and Ret as specific activated receptor tyrosine kinases and they demonstrated using functional inhibition approaches (neutralizing antibodies, antisense-mediated knockdown or small molecule inhibitors) that those specific receptors promote the in vitro behavior of metastatic osteosarcoma cell lines [32]. This evidence concerns the gene NTRK1 and osteosarcoma.