The lipopeptide FSL-1, synthesized on the basis of the N-terminal structure of a M. salivarium lipoprotein, is capable of inducing the cell surface expression of ICAM-1 in human gingival fibroblasts. It furthermore revealed an activity to induce production of monocyte chemoattractant protein 1, interleukin-6 (IL-6), and IL-8. FSL-1 also activated macrophages to produce tumor necrosis factor alpha. Overall, results by Okusawa and coworkers suggest that the diacylglyceryl and the peptide portions of FSL-1 are indispensable for the expression of biological activities and for the recognition by Toll-like receptors 2 and 6. Furthermore, the same authors conclude that the recognition of FSL-1 by Toll-like receptors 2 and 6 apparently is hydrophobic.