Carcinoembryonic antigen-related cell adhesion molecule 8 (CEACAM8) is also known as CD66b (Cluster of Differentiation 66b), CD66b, CD67, CGM6, NCA-95, and is one of seven human CEACAM family members within the immunoglobulin superfamily. CEACAM family members are a set of widely expressed proteins involved in several biological functions, including cell adhesion, migration, signal transduction, and the regulation of gene expression. Abnormal overexpression and downregulation of some CEACAMs have been described in tumor cells. In humans, CEACAMs include type I transmembrane proteins (CEACAM1, CEACAM3, and CEACAM4) and GPI-linked molecules (CEACAM5 through CEACAM8). There is no human CEACAM2. CEACAM8 is a single chain, two Ig-like C2-type (immunoglobulin-like) domains and one Ig-like V-type (immunoglobulin-like) domain. It is an activation marker for human granulocytes.