Mesenchymal component: reticulin and INI-1 pos. Desmin and SMA neg.Anaplastic ependymoma: GFAP, nestin, MAP-2, vimentin and EMA pos. Olig-2 and S-100 partially pos.Astrocytoma: GFAP, S-100 and vimentin pos. The gene discussed is SMN1; the disease is ependymoma.