Abl interactor (Abi) proteins are c-Abl-binding proteins that bind to both the Src homology 3 (SH3) domain and the C-terminal proline-rich regions of Abl kinase through dual SH3-PXXP interactions. Two highly related genes, abi-1 and abi-2, were cloned. In addition to the interaction with Abl kinase, Abi proteins also interact with other signaling molecules. Recently, it has been reported that Abi-1 dramatically promoted c-Abl-mediated tyrosine (Tyr296) phosphorylation of Mena [mammalian homologue of Drosophila Enabled (Ena)] by interacting with both proteins.Synonyms: Abelson interactor 1, Abi-1, Abl interactor 1, Abl-binding protein 4, AblBP4, Eps8 SH3 domain-binding protein, Nap1-binding protein, Spectrin SH3 domain-binding protein 1, Spectrin binding protein, e3B1