Because Ng2/Cspg4 is expressed in mesenchymal precursor cells and could play a role in regulating stem cell-like properties, and driving oncogenic mutations in Ng2/Cspg4 expressing cells results in sarcoma formation (18), we investigated the role of Ng2/Cspg4 in tumor initiation in the mouse. The gene discussed is CSPG4; the disease is sarcoma.