Serpin H1 is a serine proteinase inhibitors Which belongs to the serpin family. Serpin H1 is induced by heat shock. Serpin H1 localizes to the endoplasmic reticulum lumen and binds specifically to collagen. Thus it is thought to be a molecular chaperone involved in the maturation of collagen molecules. Autoantibodies to this protein have been found in patients with rheumatoid arthritis. Serpin H1 may be a marker for cancer and nucleotide polymorphisms in this gene may be associated with preterm birth caused by preterm premature rupture of membranes.