Lipid rafts — ordered membrane microdomains rich in glycosphingolipids and cholesterol — are implicated in both membrane sorting and signal transduction. In the acquired immune response, they appear to play an important role in T-cell activation, serving as platforms for assembly of the signalling machinery. Kathy Triantafilou and co-workers now show that rafts also function in innate immune recognition (seep. 2603). They demonstrate that several proteins involved in the cellular response to bacterial lipopolysaccharide (LPS) exist in lipid rafts: the GPI-linked LPS receptor CD14 and the heat shock proteins Hsp70 and Hsp90 are permanently present in rafts, and chemokine receptor 4 (CXCR4), growth differentiation factor 5(GDF5) and Toll-like receptor 4 (TLR4) enter rafts after stimulation of cells by LPS. The authors also demonstrate that agents that disrupt raft integrity(e.g. nystatin) block LPS-induced secretion of tumour necrosis factor α(TNF-α). They therefore conclude that that concentration of signalling molecules involved in transducing LPS-recognition signals in lipid rafts is required for an effective innate immune response to pathogenic bacteria bearing this molecule.