Toll-like receptor 4 (TLR4) is the central signaling receptor for LPS in mammals (12) . The current knowledge on the structure and function of the TLR4 has opened the possibility to develop new drug targets to fight sepsis and other diseases associated with this signaling molecule. TLR4 was identified as the first human homologue of the Drosophila Toll (13) . TLR4 not only engages LPS but it recognizes an envelope glycoprotein encoded by mouse mammary tumor virus (MMTV) (14) . In addition, TLR4 recognizes ligands such as heat shock proteins and EDA (extracellular domain A) in fibronectin (15, 16) .