Component of the extracellular signaling pathway that establishes the dorsal-ventral pathway of the embryo (PubMed:9477324, PubMed:2107028, PubMed:12493753). Three proteases; ndl, gd and snk process easter to create active easter (PubMed:9477324). Active easter defines cell identities along the dorsal-ventral continuum by activating the spz ligand for the Tl receptor in the ventral region of the embryo (PubMed:9477324). Expressed both maternally and zygotically. The clip domain consists of 35-55 residues which are 'knitted' together usually by 3 conserved disulfide bonds forming a clip-like compact structure. Activation peptide and active catalytic domain are associated by a disulfide bond. Processed easter is present in extremely low amounts in the early embryo as it is rapidly converted into a high molecular mass complex, which may contain a protease inhibitor. Zymogen activation is also controlled by a negative feedback loop from Dorsal. Belongs to the peptidase S1 family. CLIP subfamily.