We have also reported that immunotherapy of rat neu expressing breast cancer elicits neu-specific IFN-γ producing CD8+ T cells that in turn facilitate breast cancer recurrence of neu Antigen Negative Variant (ANV) tumors following initial rejection of the neu positive Mouse Mammary Carcinoma (MMC) tumor cells in immunocompetent mice [3,4]. This evidence concerns the gene ERBB2 and breast carcinoma.