The effects of PAR2 in both allergic and also nonallergic asthma have been reported to be complex, with Nicholset al. [34] demonstrating that PAR2 can act via several independent signalling pathways; proinflammatory effects are thought to be mediated through β-arrestin and protective effects are mediated through GPCR activation and increases in intracellular calcium. Here, F2RL1 is linked to asthma.