V-set and transmembrane domain-containing protein 1 is a single-pass membrane protein. VSTM1 Contains 1 Ig-like V-type domain, in humans is encoded by the VSTM1 gene. It expressed on myeloid (neutrophils, eosinophils and monocytes) but not on lymphoid cells. It behaves as a cytokine, promoting IL17A secretion by CD4+ T-cells, and differentiation and activation of IL17 producing helper T-cells (TH17). Inhibitory immune receptor involved in the regulation of phagocytes.