CD4 + T cell depletion following co-culture of P11- and P73-primed T cells with A2 + /high breast cancer cells revealed a significant larger IFN-γ response in the CD4 + depleted fraction in comparison to the CD4 + fraction (Supplementary Fig. 1), indicating that the observed P11- and P73-induced T cell activation and tumor cell killing (Figs. 3 and 4) are mediated by a cytotoxic CD8 + T cell response. Here, CD4 is linked to breast cancer.