HO1 is an enzyme which protects cells from physical, chemical, and biologic stress. In mice with diabetes and slow gastric emptying, hemin increases HO-1 activity and improves gastric emptying. Hemin is produced from red blood cells and is approved by the Food and Drug Administration for treating acute porphyria, which is an inherited condition caused by an enzyme deficiency. Hemin is not approved by the Food and Drug Administration for treating gastroparesis.