In this manuscript, Kikuchi and colleagues generated a novel, invertible gene trap cassette, termed Zwitch, which they use as a part of a methodology for conditional gene abrogation in zebrafish. In the Zwitchconstruct they included a Lens GFP marker for determining transgene incorporation. Overall, the reviewers agree that there is potentially great significance to the application of the inversible gene trap cassettes that can be integrated site-specifically as described by the authors. However, all reviewers also expressed concerns regarding the biological findings reported. As such, we would like to recommend that the authors refocus their efforts in the requested revision to expand on the details of the methods so as to make Zwitch more accessible to the interested community.