A recent study in mice has shown that TGF-β drives the differentiation of fibroblasts into collagen-producing myofibroblasts that express the collagen molecular chaperone, heat shock protein 47 (HSP47); of note, knock down of HSP47 can significantly block the process of collagen deposition in chronic GVHD (39). This evidence concerns the gene SERPINH1 and chronic graft versus host disease.