Sialomucin that may play a key role in hematopoiesis. May be involved in cell adhesion (By similarity). Promotes myogenesis by enhancing CXCR4-dependent cell motility. Positively regulates myoblast migration and promotes myoblast fusion into myotubes. Interacts with CXCR4. Expressed at high levels in the submaxillary gland and kidney, at moderate levels in the brain, heart, lung, liver, intestine, testis, muscle and bone marrow, and at low levels in the pancreas, spleen and thymus. In the ear, expressed in the inner and outer hair cells of the organ of Corti, cells of Kolliker's organ, cells in the lateral cochlear wall behind the spiral prominence and cells of the stria vascularis (PubMed:26197441). During embryogenesis, expression in found in all stages examined, with the highest levels of expression at early stages (8.5 dpc) and moderate levels of expression being found at mid- to late stages of embryogenesis. Expressed during early stages of skeletal muscle development. At embryonic stages 9.5 dpc and 10.5 dpc, expressed strongly in the dorsal somite (the structure of origin for skeletal muscle precursors). It is also expressed at later stages of muscle development;. Highly N- and O-glycosylated; contains sialic acid. Belongs to the CD164 family.