Then, B16-F10 cells were co-cultured with either of two types of cytotoxic T cells: (i) Pmel-1, which recognizes the endogenous melanoma antigen gp100, or (ii) OT-1, which, while having a low affinity for gp100, strongly recognizes Ova peptide (OVA), which was provided exogenously to tumor cells. Here, OXT is linked to melanoma.