To determine whether the antitumor effects of the anti-CTLA-4 Ab depends on direct MHC-mediated recognition of cancer cells by T cells, we generated Hepa1-6 #12 cells with beta-2 microglobulin (β2m) or MHC-II expression KO using the CRISPR-Cas9 technique. Here, CTLA4 is linked to cancer.