B2M and melanoma: To further examine the in vitro cross-dressing ability of splenic DCs, we next used an OVA gene-transduced B16 (Kb) melanoma cell line (OVA/B16) and β2m KO cells generated using the CRISPR/Cas9 system, in which we confirmed a 1 base insertion of the β2m open reading frame resulting in a frameshift mutation (Figure S3A).