Binding of S100A9 to Toll-like receptor 4 (TLR4) promotes activation of the p38 mitogen-activated protein kinase, extracellular signal-regulated kinases 1 and 2, and Jun N-terminal kinase signaling pathways, leading to myelomonocytic and monocytic AML cell differentiation[3]. Here, TLR4 is linked to acute myeloid leukemia.