Has a role in eye development. Calcium-regulated non-lysosomal thiol-protease. Present throughout development, with expression levels lower in larvae than other life stages. Mutants cause specific cells to degenerate in the developing optic lobes, resulting in the absence of certain classes of columnar neurons. Although homology to other calpains is high within the protease domain, the lack of calcium-binding sites suggests that this protein is a protease that may not be activated by calcium ions. Belongs to the peptidase C2 family.