The present invention relates to nucleotide sequences of vertebrate Serrate genes, and amino acid sequences of their encoded proteins, as well as derivatives (e.g., fragments) and analogs thereof. In a specific embodiment, the Serrate protein is a human protein. The invention further relates to fragments (and derivatives and analogs thereof) of a vertebrate Serrate which comprise one or more domains of the Serrate protein, including but not limited to the intracellular domain, extracellular domain, DSL domain, cysteine rich domain, transmembrane region, membrane-associated region, or one or more EGF-like repeats of a Serrate protein, or any combination of the foregoing. Antibodies to vertebrate Serrate, its derivatives and analogs, are additionally provided. Methods of production of the vertebrate Serrate proteins, derivatives and analogs, e.g., by recombinant means, are also provided. Therapeutic and diagnostic methods and pharmaceutical compositions are provided.In specific examples, isolated Serrate genes, from chick, mouse, Xenopus and human, are provided.