A metabolite of PGE2; does not bind effectively to EP2 and EP4 in CHO cells (Kis = 12 and 57 µM, respectively) or induce adenylate cyclase activity in CHO cells expressing these receptors (EC50s = >18 and >38 µM, respectively); levels are increased in maternal plasma in the third trimester of pregnancy and in women during and immediately after labor and delivery; levels are decreased in tumor tissue isolated from patients with NSCLC