IL4 and breast cancer: Using both spontaneous and allografted mammary tumor models in fully immune-competent mice, it was shown that dying mouse mammary tumor cells, even those occurring in the context of post-lactational involution, are cleared through MerTK-dependent efferocytosis, which drives the robust induction of immunosuppressive cytokines IL-4, IL-10, IL-13, and TGF-β [79].