RITA , a novel modulator of Notch signaling , acts via nuclear export of RBP - J

Thank you for submitting your manuscript for consideration by the EMBO Journal. It has now been seen by three referees whose comments are enclosed. As you will see, all three reviewers express significant interest in your work and are broadly in favour of publication, pending satisfactory revision. The major issue expressed to varying degrees by all the referees concerns the characterisation of the Xenopus phenotype. This is most clearly expressed by referee 2 point 1, who states that further quantitative analysis of the Xenopus phenotypes (both gain and loss of function) would be important. This also relates to the concern of referee 1 regarding the physiological significance of RITA as a Notch regulator: better data on the morphant phenotype would help to strengthen the argument that RITA is important for Notch regulation in vivo. Referee 3 also makes the point that more detailed analysis of the early neurogenesis phenotype, as opposed to the broader but more superficial characterisation of the morphants, would be valuable. Finally, this referee also requests that you provide data on the expression pattern of RITA in Xenopus, which would clearly be valuable here.