EWSR1 and Ewing sarcoma: To determine whether the causative Ewing sarcoma translocation, EWS-FLI1, influences expression of C/EBPβ in Ewing sarcoma, we transduced a Ewing sarcoma cell line (A673) with a lentivirus expressing a shRNA targeting the 3’ untranslated region (3′ UTR) of FLI1. This shRNA was previously validated and shown to specifically target EWS-FLI1 in Ewing sarcoma cells [8].