Abstract: An actin filament-binding protein 1-Afadin having the amino acid sequence of SEQ ID NO: 1 or having an amino acid sequence substantially the same as that of SEQ ID NO: 1, a cDNA sequence encoding the protein, a genomic DNA sequence to which the cDNA sequence or a partial sequence thereof is hybridized, and an antibody specifically recognizing 1-Afadin are provided. The protein is a novel actin filament-binding protein localized at the cadherin based cell-to-cell adherens junction and the other products are useful as the genetic materials for industrially utilizing the protein.