CD166 antigen is a 100-105 kD typeI transmembrane glycoprotein that is a member of the immunoglobulin superfamily of proteins, which is also known as Activated leukocyte cell adhesion molecule (ALCAM) in human, SC-1/DM-GRASP/BEN in the chicken, and KG-CAM in the rat. CD166 is a cell adhesion molecule that binds to CD6. CD166 involved in neurite extension by neurons via heterophilic and homophilic interactions.