FAP

FAP, known as fibroblast activation protein, is a type II transmembrane serine protease typically expressed at low levels in normal tissues but significantly elevated under pathological conditions such as fibrosis, arthritis, and cancer. FAP's role in promoting tumor cell proliferation, invasion, angiogenesis, and immunosuppression is well-documented. It binds to 尾-integrin, enhancing tumor cell proliferation, migration, and invasion, while its angiogenic properties stem from its dipeptidyl peptidase activity, which cleaves neuropeptide Y to promote angiogenesis and endothelial cell migration. FAP's downstream signaling pathways include PI3K/AKT, RAS/ERK, SHH/GLI, and FAK.