TYRP1 and melanoma: However, the amount of IL-2 produced by TRP1-specific T cells from Ag+GILT-/-Tg mice in the presence of a PD-1 blocking antibody was still significantly reduced in comparison to T cells from Ag-GILT+/+Tg mice (Fig 5), suggesting that PD-1 blockade alone may not be sufficient to completely restore the effector function of melanoma-specific T cells.