KDR and osteosarcoma: To first establish the expression patterns of VEGFR2 and its associated ligands in our pediatric cancer models, we profiled a panel of 11 pediatric cancer cell lines representing neuroblastoma (IMR-32, KELLY, SH-SY5Y), retinoblastoma (Y79), osteosarcoma (HOS, Saos-2, SJSA-1), rhabdomyosarcoma (SJCRH30 [alveolar RMS], RD [embryonal RMS]), malignant rhabdoid tumor (A-204), and Ewing’s sarcoma (RD-ES) for VEGFR2 protein expression (Figure 1A).