- A novel synthetic acyclic lipid A-like agonist activates cells via the lipopolysaccharide/toll-like receptor 4 signaling pathway. Lien, E., Chow, J.C., Hawkins, L.D., McGuinness, P.D., Miyake, K., Espevik, T., Gusovsky, F., Golenbock, D.T. J. Biol. Chem. (2001)