ERBB2 and breast cancer: This ErbB2 ortholog restriction is evident in the immune response elicited by the vaccines to both challenges with syngeneic tumor cells expressing the distinct ErbB2 ortholog, and autochthonous mammary cancer, at least for those appearing in rat ErbB2 transgenic mice [24], since RRT plasmid was not used in human ErbB2 transgenic mice developing autochthonous tumors (Table 1).