MYCN and Ewing sarcoma: In addition to Ewing sarcoma cells, we also tested PVS engraftment of a neuroblastoma cell line with MYCN oncogene amplification, SK-N-BE(2)C (engineered to express H2B-GFP) and a patient-derived culture of neuroblastoma bone marrow metastasis, STA-NB-8 (MYCN amplified, ALK mutated).