Wingless Type MMTV Integration Site Family, Member 9A (WNT9A)

WNT9Ais expressed in gastric cancer cell lines. The protein encoded by this gene shows 75% amino acid identity to chicken Wnt14, which has been shown to play a central role in initiating synovial joint formation in the chick limb. This gene is clustered with another family member, WNT3A, in the chromosome 1q42 region. Wnt14 plays a central role in initiating synovial joint formation in the chick limb. Wnt14 was expressed in joint-forming regions prior to the segmentation of the cartilage elements, and local misexpression of Wnt14 induced morphologic and molecular changes characteristic of the first steps of joint formation. Induction of an ectopic joint-like region by Wnt14 suppressed the formation of the immediately adjacent endogenous joint, potentially providing insight into the spacing of joints.