Plays a role in somitogenesis. Required for somite segregation and establishment of rostrocaudal polarity in somites. Expressed in the embryonic anterior presomitic mesoderm. First expressed in S-I at 8.5 dpc, where expression is maintained until 13.5 dpc, with an additional stripe of expression sometimes seen in the rostral part of S0 and S-I. By MESP2, and acts in a negative feedback loop with MESP2, functioning negatively toward MESP2 to regulate NOTCH signaling in the anterior presomitic mesoderm. The ripply homology domain is required for transcriptional repression. The WRPW motif is required for binding to tle/groucho proteins. Belongs to the ripply family. Intron retention.