MCA-205/Cre cells are derived from the mouse fibrosarcoma cell line MCA-205 by stably integration of a constitutive Cre recombinase stably expression construct. MCA-205 cells are widely used for studying tumor-reactive T lymphocytes, the most critical requirement for adoptive immunotherapy. MCA-205/Cre cells stably express a nuclear localized Cre recombinase.