FGL1 (Fibrinogen-Like Protein 1) is a protein that belongs to the fibrinogen-related protein superfamily. This family of proteins shares structural similarities with fibrinogen, a major component of blood clots, but they have diverse functions beyond coagulation. FGL1 is expressed in various tissues and cell types, including immune cells such as macrophages and dendritic cells. It has been implicated in several biological processes, particularly in the immune system. One of its key roles is in the regulation of innate and adaptive immune responses. FGL1 has been shown to interact with several immune receptors and molecules, modulating their signaling pathways. For example, it can bind to certain inhibitory receptors on immune cells, such as TIGIT (T-cell immunoreceptor with Ig and ITIM domains), and mediate immune suppression. This interaction is thought to contribute to the regulation of immune tolerance and the prevention of autoimmune diseases. In addition to its role in immune regulation, FGL1 has also been linked to cancer biology. Studies have shown that FGL1 expression is altered in some cancer types, and it may play a role in tumor growth, metastasis, and immune evasion.