TLR9 and idiopathic pulmonary fibrosis: Indeed, the induction of EMT observed after CpG treatment of alveolar cells is absent after TLR9 silencing (115) but their upregulation of CCN1, a matricellular protein with pleiotropic functions implicated in IPF and experimental lung fibrosis (116), is predominantly linked to CpG-induced endoplasmic reticulum-(ER) stress (117).