TGFA and primitive neuroectodermal tumor: To assess the pathological function of Tgf-α in PNET tumors, we compared the proliferation index (assayed by phospho-Histone H3 staining—Fig. 4E), blood vessel density (assayed by measuring areas of Meca-32 staining— Fig. 4F), and apoptotic index (assayed by TUNEL staining—Fig. 4G) of wild-type versus waved-1 mutant tumors.