CD40 and Ewing sarcoma: Lollini et al. (1998) analyzed the expression of CD40 in 12 human osteosarcoma cell lines, six ES lines, and five rhabdomyosarcoma lines by flow cytometry. CD40 was highly expressed in osteosarcoma and ES, and was closely related to ES prognosis. CD70 is a therapeutic target for osteosarcoma (Pahl et al., 2015); however, its role in ES pathogenesis is currently unclear. CD276 is an immunotherapy target for peritoneal cancer, glioma, and central nervous tumors (Picarda et al., 2016), and its role in ES is also unclear.