Component of the TLR4 signaling complex. Mediates the innate immune response to bacterial lipopolysaccharide (LPS) leading to cytokine secretion. Belongs to the lipopolysaccharide (LPS) receptor, a multi-protein complex containing at least CD14, MD-2 and TLR4. Interacts with TLR4; this interaction is greatly enhanced by LPS stimulation. Interacts with LPS. Highly expressed in the brain, ovary, small intestine and spleen. By bacterial lipopolysaccharides (LPS). N-glycolysaled. Extended N-terminus.