Probable cell adhesion protein involved in leukocyte transmigration across the blood-brain barrier. Does not express any beta-galactosyltransferase activity in vitro. Ubiquitous. Highly expressed in secretory and nervous tissues. Belongs to the glycosyltransferase 25 family. Has no glucosyltransferase activity. Concerning beta-galactosyltransferase activity, the level of CERCAM could be too low to detect any activity when tested in transfected insect cells.