In recent years there has been increasing evidence that type I cDCs (cDC1) are required to prime tumor-reactive T cells within the TME, especially in patients treated with immune checkpoint inhibitors.3 cDC1s are a rare type of dendritic cells that, once mature, display high levels of MHC-I, MHC-II, CD40, and lineage-specific markers XCR1 and CLEC9A. The gene discussed is XCR1; the disease is neoplasm.