The Toll-like receptors (TLRs) represent the prototype pattern recognition receptors (PRRs) characterized by a high degree of evolutionary conservation.

In humans, TLRs can be grouped into the TLR1,-2,-6, -10 and the TLR7-8, -9 subfamilies, while TLR3-4, and -5 appear phylogenetically more isolated. Takeda K., et al. 2003, Annu.Rev.Immunol.2003, 21-335

IL-1R-associated kinases (IRAKs) are important mediators in the signal transduction of Toll / IL-1R (TIR) family members. Cao Z., et al.,1996, Science, 271-5252. IRAK-4 (IL-1 receptor-associated kinase-4) is recruited after TLRs triggering. Li S., et al.,2002, PNAS, 99,5567-5572