Heat shock protein 47, also known as SERPINH1 is a serpin which serves as a human chaperone protein for collagen. This protein is a member of the serpin superfamily of serine proteinase inhibitors. Its expression is induced by heat shock. HSP47 is expressed by cells present in Endoplasmic Reticulum. These cells synthesize and secrete type I and type II collagen. The protein localizes to the endoplasmic reticulum lumen and binds 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. Heat shock protein 47 has been shown to interact with collagens I, II, III, IV and V. In the ER, HSP47 interacts with and stabilizes correctly-folded procollagen. Nucleotide polymorphisms may be associated with preterm birth and Osteogenesis Imperfecta type X. Serpin-H1 is up-regulated in several cancers including squamous cell carcinoma, breast and prostate carcinomas. Expression in tumors drives malignant growth and invasion by enhancing deposition of extracellular matrix proteins.