Might be involved in growth regulation, and in myelinization in the peripheral nervous system. Schwann cells of the peripheral nervous system (PubMed:1552943). Expressed at growth arrest of mammalian fibroblasts (PubMed:1692961). Expressed from day 3 of gastrulation, expression levels are maintained until day 10. A defect in Pmp-22 is the cause of trembler (tr) phenotype. Trembler mice show a Schwann cells defect characterized by severe hypomyelination and continuing Schwann cells proliferation throughout life. Belongs to the PMP-22/EMP/MP20 family.