Isoform neural may associate with CadN and participate in the transmission of developmental information. Can associate with alpha-catenin. Isoform cytoplasmic 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. Interacts with Mer and Moe at the adherens junction (PubMed:8666669). Interacts with Inx2 (PubMed:15047872). Interacts with alpha-Cat (PubMed:25653389). Interacts with Myo31DF (PubMed:16598259, PubMed:22491943). Inner surface of cell membrane and adherens junction. Isoform cytoplasmic accumulates at low levels in axons, at high levels in specific cells along the CNS midline and in leg and eye imaginal disks. Isoform neural accumulates in the axon tracts of the CNS. Both isoforms accumulate in the peripheral nervous system. Present at all stages, but reaches the highest levels during early to mid-embryogenesis. Isoform cytoplasmic is the predominant one from the cellular blastoderm stage until germ-band retraction. Isoform neural is first seen after germ band retraction. Phosphorylated on Ser, Thr and Tyr residues (PubMed:7529201). Level of phosphorylation varies both during embryonic development and from embryonic tissue to tissue (PubMed:7529201). Sgg is required for phosphorylation and wg signal negatively regulates arm phosphorylation (PubMed:7529201). Hypophosphorylated form of arm increases in steady-state levels (PubMed:7529201). Phosphorylated directly or indirectly by CkIalpha which stimulates its degradation (PubMed:11927557). Belongs to the beta-catenin family.