May associate with CadN and participate in the transmission of developmental information. Can associate with alpha-catenin. Accumulates through wg signaling; arm function in wg signal transduction is required early in development for determination of neuroblast fate. Arm and Abl proteins function cooperatively at adherens junctions in both the CNS and epidermis (By similarity). Inner surface of cell membrane and adherens junction. Belongs to the beta-catenin family.