DES and neoplasm: Histologically, the ASPcKOP7cKO tumor cells stained sporadically for DESMIN but were no longer positive for RMS diagnostic markers MYOD1 and MYOGENIN; this was specific for ASPcKOP7cKO tumors as ASPcHetP7cKO and ASPcKOP7cHet tumors were still myogenic, small round blue tumors consistent with RMS (Fig. 7d).