- Kdo2-Lipid A of Escherichia coli, a defined endotoxin that activates macrophages via TLR-4. Raetz, C.R., Garrett, T.A., Reynolds, C.M., Shaw, W.A., Moore, J.D., Smith, D.C., Ribeiro, A.A., Murphy, R.C., Ulevitch, R.J., Fearns, C., Reichart, D., Glass, C.K., Benner, C., Subramaniam, S., Harkewicz, R., Bowers-Gentry, R.C., Buczynski, M.W., Cooper, J.A., Deems, R.A., Dennis, E.A. J. Lipid Res. (2006)