PTGER2 and idiopathic pulmonary fibrosis: In some fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF), the inhibition of PGE2 expression in myofibroblasts was due to the decreased expression of the prostaglandin E receptor 2 (PTGER2), the major G protein-coupled receptor of PGE2 [20, 21].