KDR and chordoma: Although RTKs relay crucial signals during embryo development, as underlined by the severe developmental defects caused by notochord-focused misexpression of FGFR, Kit and PDGFR genes (Fig. S3A-D), the repeatedly chordoma-associated EGFR and KDR are, in our assay, individually sufficient to transform developmental notochord cells (Fig. 3E-H).