Potently contracts gastrointestinal (GI) smooth muscle. Induces proliferation, migration and fenestration (the formation of membrane discontinuities) in capillary endothelial cells. Induces proliferation and differentiation, but not migration, of enteric neural crest cells. Directly influences neuroblastoma progression by promoting the proliferation and migration of neuroblastoma cells. Positively regulates PTGS2 expression and prostaglandin synthesis. May play a role in placentation. May play a role in normal and pathological testis angiogenesis. Highly expressed in liver and ovary and weakly expressed in testis and placenta. Expressed in mucosa and mesenchyme of embryonic gut during enteric nervous system development (at protein level). Predominantly expressed in kidney and liver. Also expressed in lung, ovary, placenta and testis. In fetal liver, is restricted to and highly expressed in hepatocytes. In adult kidney, expression is restricted to the endothelial tubule cells. In placenta, expressed throughout gestation. In placenta, at 7.5 dpc highly expressed in ectoplacental cone, endoderm and in giant cells, and at 9.5 dpc restricted mainly to the labyrinth layer (at protein level). In placenta, most highly expressed during early gestation (between 9.5 and 10.5 dpc). Belongs to the AVIT (prokineticin) family.