Indeed, IL-38 overexpression reduced CD8+ T cells infiltration in subcutaneously (s.c.)implanted lung tumors, and IL-38 blockade increased immune cell infiltration, leading to better tumor growth control in s.c. implanted EMT6 murine breast cancer and B16.F10 murine melanoma models.18 34 The present study shows that both, genetic ablation and pharmacological blockade of IL-38 in models where tumors develop endogenously over a longer period of time, is equally effective in promoting potentially cytotoxic immune cell infiltration. Here, IL1F10 is linked to breast carcinoma.