To see whether inhibition of NF-κB activity results in the induction of apoptotic cell death and expression of NF-κB target apoptotic cell death regulatory protein, the levels of apoptotic cell death and expression of apoptotic cell death regulatory proteins were assessed. Apoptotic cell death in the tumor sections were evaluated in the CCR5+/+ and CCR5−/− mice that were inoculated with melanoma cells. TUNEL staining revealed a higher frequency of apoptotic cell death in the tumor tissues of the CCR5−/− mice than that of the CCR5+/+ mice (Figure 3A). Immunohistochemical and immunofluorescence showed that high levels of cleaved caspase-3 and Bax were found more frequently in the CCR5−/− mice than in the CCR5+/+ mice (Figure 3B and 3C). Consistent with the immunohistochemical data, Western blot analysis of tumor proteins showed greater increased levels of cleaved caspase-3, cleaved caspase-9, cleaved PARP and Bax, whereas the levels of Bcl-2 and C-IAP1 were significantly decreased in CCR5−/− mice tissues (Figure 3D).