SLC15A4 and neoplasm: SLC15A4 is required for Toll-like receptor 7 (TLR7)- and TLR9-mediated type I interferon (IFN-I) production in plasmacytoid dendritic cells (pDCs) by the mTOR pathway, highlighting its role in regulating the immune response in the tumor microenvironment (Kobayashi et al., 2014).