Required to establish coherent arrays of polarized cells and segments in embryos. Plays a role in wingless (wg) signaling, possibly through the reception of the wg signal by target cells and subsequent redistribution of arm protein in response to that signal in embryos. This signal seems to be required to establish planar cell polarity and identity. Interacts with nkd. This interaction may require zinc. Associated with the membrane when hyperphosphorylated. Found in egg chambers of the ovary and ubiquitously throughout embryogenesis and in disks. Expression is not seen in salivary glands, muscles or ventral ganglia but is observed in brain lobes. Expressed at high levels at 0-1 hour and from 5-17 hours. Also expressed at high levels in early pupae. Phosphorylated. Wg signaling generates the hyperphosphorylated active forms. Belongs to the DSH family.