TMPRSS4 and Ewing sarcoma: MCAM and TMPRSS4, localized in the chromosomal region 11q13.3–11q25, play a role in invasion, metastasis, migration, and adhesion; of considerable interest, there is also Fli-1, which plays an important role in erythropoiesis; in particular, the expression of the EWS/Fli-1 fusion gene has been shown to be critical for cancer induction in the majority of Ewing’s sarcomas [34,35].