PAR1 and PAR2 signaling involves MAPK and PI3K signaling pathways in the induction of innate immune responses. Protease-activated receptors are G-protein-coupled receptors. Once activated, they signal via ERK1/2 and p38 MAPK to induce innate immune responses. This action is limited by activation of PI3K-Akt signaling pathway. This inhibitory effect is predominantly via blocking of p38 activation.