This is a substrate peptide for Interleukin-1 Receptor-Associated Kinase (IRAK) 4, derived from the IRAK-1 activation loop peptide amino acids 360 to 380. This peptide sequence contains Ser-376, one of the primary phospho-acceptor residues of IRAK-1. IRAK-4 phosphorylates IRAK-1 as a key step in regulation of inflammatory signaling pathways.