CD248 and neuroblastoma: Next, we tested the cytotoxic activity of ENDOS/ADC in four human tumor cell lines expressing different levels of endosialin: high (osteosarcoma SJSA-1), intermediate (neuroblastoma SKNAS and Ewing's sarcoma A-673), or not expressing endosialin (metastatic A375 melanoma cells) (Figure 2D upper panel).