PTK2 and cholangiocarcinoma: L1CAM is a transmembrane glycoprotein that has been reported as highly expressed in 40.5% (17/42) of patients with poorly differentiated ICC, and loss of L1CAM markedly reduces the tumor growth and metastatic ability of CC cells in vivo and in vitro by inhibiting focal adhesion kinase (FAK) and AKT activation [64].