RAG1 and melanoma: To address whether Lsp1-manipulated (eg, gene-edited) T cells have therapeutic potential and to confirm that the Lsp1 gene in T cells is required for melanoma growth, we performed adoptive transfer experiments using Lsp1 KO and Lsp1 Tg T cells in Rag1 KO mice, which are deficient in mature T and B cells.34 Prior to the adoptive transfer, we confirmed that Lsp1 KO T cells and Lsp1 Tg T cells had a similar ratio of CD4/CD8 in CD3+ T cells (figure 6A).