SYP and neoplasm: Staining for Synaptophysin, a marker of neuronal cells clearly defined the boundaries of the tumor bed (Fig. 3B, oHSV-1, Fig. 4, oHSV-1 treated; Synaptophysin), and of the tumor area in GL261-untreated mice (Figs. 3B and 4, vehicle; Synaptophysin).