TLR4 and neoplasm: Bacterial lipopolysaccharides (LPS) are present in both cancer cells and immune cells of TME [11], which can bind to the TLR4 of monocytes, causing them to differentiate into an immunosuppressive M2 phenotype [12, 13]; and can also promote the recruitment of CD11b+Gr-1+ myeloid-derived suppressor cells (MDSCs) and CD1d+CD5+ regulatory B (Breg) cells on tumor cells, which together inhibit the local anti-tumor T cells response [14].