ERBB2 and neoplasm: However, immune cells from 4T1.2/HER2 tumor-cured mice and 4T1.2/HER2 tumor-bearing mice with smaller tumors induced a more than 2-fold increase in IFN-γ production mainly in response to 2 of the HER2 class I peptides tested, HER263–71 and HER2342–350.