PTT inhibits tumor growth in SS.BN3IL2Rγ- (DLL4-low) but not SSIL2Rγ- (DLL4-high). To assess the impact of the TME vascular heterogeneity on PTT, SS.BN3IL2Rγ- and SSIL2Rγ- rats aged 4-6 weeks were orthotopically implanted with 6 x 106 of luciferase expressing MDA-MB-231(231LUC+) triple negative breast cancer cells in the inguinal mammary fat pad. The gene discussed is DLL4; the disease is neoplasm.