CpG-ODN, being a TLR9 agonist, may rapidly stimulate T and B cells, induce Th1 cytokines [interleukin (IL)-1, IL-6, IL-12, IL-18, TNF-α and IFN-γ] and promote the maturation of antigen-presenting cells (APCs), indirectly activate immune cells and inhibit tumor proliferation. Here, TLR9 is linked to neoplasm.