In the remaining 15% of ES cases, other fusion genes have been described, mainly involving the EWS gene with other members of the ETS family (Zucman et al., 1993; Jeon et al., 1995; Kaneko et al., 1996; Peter et al., 1997; Shing et al., 2003; Ng et al., 2007), with 10% of these cases characterized by the formation of the EWS-ERG fusion protein (Zucman et al., 1993). Here, EWSR1 is linked to Ewing sarcoma.