vang-like protein 2-B protein strabismus-B stb1 vangl2-a van Gogh-like protein 2-B xstrabismus-B Ltap stbm1 Van Gogh vang vangl2-b lpp1 vangl2 xstbm-B Xstrabismus vang-like 2 (van gogh, Drosophila) b vangl2b stbm-a van gogh-like2 vang-like 2 b stbm strabismus