Vasorin (VASN) is a single transmembrane type I membrane protein, also known as Slit-like 2 protein (SLITL2). It is mainly expressed in vascular smooth muscle cells and participates in many pathophysiological processes. VASN contains an EGF-like domain, ten leucine-rich repeats (LRR) and a transmembrane domain. VASN is considered as a negative regulator of transforming growth factor -\(\beta \) (TGF-\(\beta \)) signal. It may be involved in regulating cell growth, differentiation and epithelial-mesenchymal transition (EMT) by binding and regulating the activity of TGF-\(\beta \). In blood vessels, VASN is expressed in vascular smooth muscle cells, which has the characteristics of protecting blood vessels and can negatively regulate cell migration and proliferation caused by vascular injury. VASN is also involved in the reaction of cells to hypoxia and redox state, and plays a certain role in alleviating cell stress damage. Because of its high expression in specific tissues (such as blood vessels and some solid tumors), VASN is often used as a molecular marker to study vascular diseases or pathological changes of tumors. The protein has multiple bands, intact vasorin (∼100 kDa) and a soluble fragment (∼75 kDa),Cleaved frament (~50-60 kDa) (PMID: 29930755).