TLR9 and neoplasm: In the construction of tumor vaccines, these nanoparticles enhance the maturation and activation of dendritic cells to stimulate specific antitumor immune responses and efficiently target and stimulate the maturation of DCs by modifying the TLR9 agonist, CpG oligonucleotides, and aptamers on tumor cell membrane vesicles to generate long-lasting antitumor immune responses (24).