16,16-dimethyl PGE2 is a competitive inhibitor of 15-hydroxy PGDH, but it is not a substrate for the enzyme.{1789} Because of its resistance to metabolism by 15-hydroxy PGDH, it has a prolonged half-life in vivo. 16,16-dimethyl PGE2 acts as an agonist on most EP receptor subtypes, and has been used experimentally to induce cervical ripening, uterine contraction, and prevent ulceration of the gastric mucosa in rats and dogs.{437,1422} The Kd for activation of isolated EP2 receptors is about 1 nM.{1422} 16,16-dimethyl PGE2 can be used to preserve the self-renewal properties while preventing the differentiation of hematopoietic stem cells during expansion in culture.{27133,27095}