Rhomboid protease-like protein which has no protease activity but regulates the secretion of several ligands of the epidermal growth factor receptor. Indirectly activates the epidermal growth factor receptor signaling pathway and may thereby regulate sleep, cell survival, proliferation and migration. Specifically expressed in the nervous system and in brain. Expressed exclusively in the central nervous system of embryos. In the third instar larva, expression is also restricted to neural tissue with specific expression behind the morphogenetic furrow in the developing eye and in the optic lobes within brain. Flies display a severe decrease in daytime activity pattern and an increase in sleeping periods. Belongs to the peptidase S54 family.