GZMB and breast cancer: In addition, a significant increase in infiltrating CD8+ T cells, as well as expression of IFN-γ and granzyme B by CD8+ T cells was observed in non-treated tumors derived from MMTV-PyMT transgenic mice that received Ad5-CTV (Figure 6A to 6E), suggesting that Ad5-CTV treatment induced a systemic immune response against all the mammary tumors within the MMTV-PyMT transgenic mouse model.