SHISA4 Antibody: SHISA4 plays an essential role in the maturation of presomitic mesoderm cells by individual attenuation of both FGF and WNT signaling. The Shisa family of single-transmembrane proteins is characterized by an N-terminal cysteine-rich domain and a proline-rich C-terminal region. Its founding member, Xenopus Shisa, promotes head development by antagonizing Wnt and FGF signaling. Shisa physically interacted with immature forms of the Wnt receptor Frizzled and the FGF receptor within the ER and inhibited their posttranslational maturation and trafficking to the cell surface. Loss of Shisa function sensitized the neuroectoderm to Wnt signaling and suppressed head formation during gastrulation.