Component of the extracellular signaling pathway that establishes the dorsal-ventral pathway of the embryo (PubMed:9618496, PubMed:9477324, 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). Expression begins in previtellogenic stages and is seen in germline-derived nurse cells of the germarium. Expression continues throughout oogenesis with transcripts from the nurse cells accumulating in the oocytes. Most abundant in the ovaries, the level of protein decreases from the moment of egg laying and is essentially gone by 4 hours. Expressed both maternally and zygotically. Belongs to the peptidase S1 family. Truncated N-terminus. Intron retention. Extended N-terminus.