By overlaying dark field imaging of NPs with immunofluorescent imaging of tumor blood vessels, we found marked differences in intratumoral distribution of NPs in tumors growing in the SS.BN3IL2Rγ- host (low-DLL4) compared with the SSIL2Rγ- host (high-DLL4) (Figure 5). This evidence concerns the gene DLL4 and neoplasm.