Prostaglandin E2 (PGE2) signaling via E prostanoid (EP) receptors EP2/EP4 inhibits fibroblast collagen gel contraction. (A) normal adult counterpart, and (B) subglottic stenosis fibroblast contraction was assayed in the presence or absence of PGE2 and/or butaprost (BUTA) over a 24-hour time period. All contraction assays were performed in regular fibroblast media (DMEM) supplemented with 2% fetal bovine serum, without agents (CNT) or with PGE2 (PGE2, 1 μm) or butaprost (EP2 agonist) (BUTA, 1 μm). Data points differing from the control value are indicated by: * PGE2, P <.05; + BUTA, P <.05 using Student t test.