CD47 and osteosarcoma: Cancer cells exploit the “don't eat me” function of CD47 by expressing higher levels of CD47 on their surface compared with non-malignant cells; numerous studies have shown that CD47 is overexpressed in different types of tumors (16), including in myeloma (29), leiomyosarcoma (30), acute lymphocytic leukemia (31), non-Hodgkin's lymphoma (32), breast cancer (33), osteosarcoma (34), and head and neck squamous cell carcinoma (23).