Figure 2: IL-33/ST2 system. IL-33 recognition by ST2L promotes receptor dimerization with IL1RAcP and recruitment of receptor complex components, MyD88, TRAF6, and IRAK1-4, to intracellular TIR domain. Furthermore, protein phosphorylation favors NF-κB and MAPK pathway activation. When sST2 is translated and secreted to the extracellular media, it sequesters IL-33 and inhibits binding to ST2L as a decoy receptor.