Activation of the Toll pathway is different between vertebrates and invertebrates, in which the former is directly activated by Toll-like receptors (TLRs) binding to various pathogen-associated molecular patterns (PAMPs) from different pathogens, and the latter is indirectly activated by pathogen infection where Toll receptors bind to the cytokine-like molecule Spätzle but not to PAMPs. The gene discussed is TLR4; the disease is infection.