The Vang family of proteins are integral membrane proteins that are homologues of the Drosophila tissue polarity gene strabismus. The gene encoding for Van Gogh-like protein 1 (Vangl1), also designated Strabismus 2 (STB2), localizes to human chromosome 1p11-p13.1. Van Gogh-like protein 2 (Vangl2), also designated Strabismus 1 (STB1), localizes to chromosome 1q22-q23. Vangl1 is expressed primarily in testis and ovary, but is also expressed in gastric and pancreatic cancer. Vangl proteins play a key developmental role in establishing planar cell polarity (PCP) and in regulating convergent extension (CE) movements during embryogenesis. Vangl1 and Vangl2 are both downregulated in several cancer cell lines and primary tumors.