HLA-E and Ewing sarcoma: Therefore, HLA-E and -F but not full-length HLA-G are transcriptionally expressed in a fraction of PDX models of pediatric solid tumors, particularly in Ewing sarcoma and HGG, respectively, in agreement with reports in Ewing sarcoma (81) and adult gliomas (82) for HLA-E, and may contribute to HLA-dependent immunomodulation in these tumors.