FOXP3 and melanoma: We confirmed this in C57BL/6 Foxp3EGFP mice in which Foxp3/Treg are identified by EGFP expression; in these mice an IRES-linked EGFP is bicistronically co-expressed with Foxp3 under control of the endogenous Foxp3 promoter/enhancer.[29] B16 melanoma was propagated subcutaneously in these mice.