TLR9 and cancer: At present, dendritic cells and antigen presenting cells (such as macrophages) can be strongly stimulated by CpG and AT oligodeoxynucleotides, CpG and AT can recognize and bind to TLR9 of the Toll-like receptor family, thereby inducing Th1 immune response, up-regulating the level of anti-cancer immune response, and inhibiting the development of cancer (Bohle et al., 1999; Shimosato et al., 2005).