To demonstrate that the lack of anti-melanoma activity in Ag+GILT-/-Tg mice is due to T cell tolerance rather than deficient MHC class II-restricted processing of TRP1 by GILT-deficient APCs, we adoptively transferred CD4+ T cells from Ag-GILT+/+Tg and Ag+GILT-/-Tg mice into Ag-expressing RAG1-/- mice with and without GILT. This evidence concerns the gene RAG1 and melanoma.