Phosphoprotein associated with glycosphingolipid-enriched microdomains (PAG), also known as Csk-binding protein (Cbp), is a ubiquitously expressed transmembrane adaptor protein present in lipid rafts and involved in a number of signaling pathways. It helps recruit cytoplasmic C-terminal Src kinase (Csk) to lipid raft-associated Src kinases, mediates a link to actin cytoskeleton and interacts with several other important cytoplasmic and plasma membrane-associated proteins. In recent years, PAG has been implicated in various aspects of cancer cell biology. Our review covers all so far published data on this interesting protein.