Recently, aspr has been shown to positively regulate Notch signaling. It has sequence similarity to mammalian Jagged, but unlike Jagged and other Notch ligands it lacks a transmembrane domain and DSL (Delta, Serrate and LAG-2) domain (FBrf0245945). It is unclear if aspr can act as a ligand for N and therefore has not included in the NOTCH LIGANDS gene group.