- Drosophila head segmentation factor buttonhead interacts with the same TATA box-binding protein-associated factors and in vivo DNA targets as human Sp1 but executes a different biological program. Schöck, F., Sauer, F., Jäckle, H., Purnell, B.A. Proc. Natl. Acad. Sci. U.S.A. (1999)