ASPN and neoplasm: Asporin (ASPN) was the first member of the small leucine-rich proteoglycan (SLRPs) family to be discovered, and it has been linked to collagen fibrillogenesis, signal transduction, and tumor growth.[1] SLRPs play an important role in extracellular matrix (ECM) homeostasis and collagen behavior by regulating collagen fibrillation and binding to transforming growth factor-β (TGF-β) and other ligands and receptors in a complex manner.