Negatively regulates aortic matrix metalloproteinase-9 (MMP9) production and may play a protective role in vascular remodeling. Expressed in most tissues except spleen, thymus and testis. Mice (older than 14 months) are prone to aortic dilation as well as cystic medial degeneration (CMD). Due to non-canonical splice donor and acceptor sites. Belongs to the BI1 family. LFG subfamily.