GLI1 and neoplasm: Although NPE and PE RMS depend on the combination of Ptch1+/− and ETV7TG+/− for tumor specification and growth, the addition of Neu1 haploinsufficiency drastically increased Myc expression, the marker of proliferation, and the downstream effectors of the SHH pathway, Gli1 and Gli2, known to be associated with metastatic growth (Fig. 6e).