Part of the Notch signaling pathway. Mesectodermal expression appears shortly before the onset of gastrulation. Later it is detected in the neuro-ectoderm as well as in the mesoderm in a highly dynamic pattern in many stages of embryogenesis. In imaginal disks, expressed as following: in the eye disk, within and posterior to the morphogenetic furrow; in the wing pouch, in the presumptive intervein regions and wing margin; in the leg disk, general expression. Belongs to the M4-like protein family.