Figure 1. Effect of TAM family members on the immune response to cancer cell death.

Activation of Axl or Mertk on cancer cell results in suppression of antigen processing and presentation to T cells, while Mertk on tumor macrophages results in phagocytosis of dying cells to the exclusion of dendritic cell uptake. Cell uptake drives suppressive differentiation of macrophages, which can, in turn, suppress T cells in the tumor environment. Where TAM family members are absent, antigen is more available for uptake by dendritic cells that can expand naive T cells that can traffic to the tumor. Tumor-infiltrating T cells find decreased macrophage suppression and increased antigen presentation, permitting increased control of tumors.