The expression of the selected target genes in Ewing’s sarcoma (CAV1, NR0B1, IGFBP3 and TGFBR2), together with the expression of HIST1H4L, KCNN2, ECRG4 and LDOC1, was then validated in an independent series of PCa with and without ETS gene fusions, as well as in a series of ESFT and ARMS. The gene discussed is ECRG4; the disease is Ewing sarcoma.