Immune suppressive molecule that inhibits antigen-specific T-cell activation by acting as a major ligand of LAG3 (PubMed:30580966). Responsible for LAG3 T-cell inhibitory function (PubMed:30580966). Binds LAG3 independently from MHC class II (MHC-II) (PubMed:30580966). Secreted by, and promotes growth of, hepatocytes (PubMed:11470158, PubMed:19880967). Homodimer (PubMed:11470158). Interacts (via the Fibrinogen C-terminal domain) with LAG3 (via Ig-like domains 1 and 2) (PubMed:30580966). Secreted in the blood plasma. Under normal conditions, liver-specific. Expression is induced by interleukin-6 (IL6) (PubMed:18039467). Up-regulated in a number of cancers, such as lung cancer, prostate cancer, melanoma and colorectal cancer (PubMed:30580966).