B2M and breast carcinoma: In fact, EO-NY-derived β2m knock-out variants have been established [17] that could be used as parental cell lines to generate stable cell transfectant clones co-expressing NY-BR-1 in combination with the transgenic HLA molecule, resulting in NY-BR-1 expressing breast cancer cell lines that might allow performance of tumor protection and regression experiments in HLA-double transgenic mice co-expressing HLA-DR4 and HLA-A2 [32].