CD34 and Ewing sarcoma: Immunophenotyping was also performed on single-cell suspensions of Ewing sarcomas established in the hu-CD34+ model, and results demonstrated low baseline infiltration of hu-CD45+ cells in Ewing sarcomas (Fig. 2E), similar to the level of immune infiltration noted in patient Ewing sarcomas at baseline (Supplementary Table S4; refs. 43, 44).