Upon DNA transfection of murine B16.F1 melanoma and CT26.CL25 colorectal carcinoma cells, we assessed the activity of secreted IL15 by incubating the CTLL‐2 murine cytotoxic T lymphocytes with media from transfected B16.F1 and CT26.CL25 cells (Fig 5B). Here, IL15 is linked to melanoma.