LRRC19 is a member of the extracellular leucine-rich repeat superfamily, a family of proteins that are thought to have diverse functions such as cell adhesion, signaling, and innate immunity. LRRC19 is closely related to the Toll-like receptors (TLRs), especially TLR3. LRRC19 does not contain a cytoplasmic Toll/IL-1 receptor (TIR) domain, but can activate NF-kappaB and induce the production of proinflammatory cytokines after stimulation with the TLR3 and other TLR ligands, suggesting that LRRC19 may play a role in the recognition and the response to certain pathogenic microorganisms. LRRC19 has also been suggested to be a potential biomarker for pancreatic tumor sensitivity to the anti-cancer, small molecule Src inhibitor AZD0530.