TLR9 and neoplasm: cDC1s promote the cross-presentation of tumor antigens to CD8+ T cells and are critical for the generation of cytotoxic effector T cell responses, while cDC2s are involved in the activation of T helper type 2 cells, and pDCs highly express TLR-9 and are copious producers of IFN-I when TLR-9 is stimulated36,41,42.