Elation, excitement, relief, pride. Work that was begun more than 5 years ago has finally seen the light of day! We still have many questions, but our current insights into how two extrinsic signals – Gdf6a and the retinoic acid (RA) – influence the transition from proliferation to differentiation in the vertebrate eye is now published in Development. With the help of many collaborators, including Reed undergrads (Amanuel, Terra, Audrey, Wilson, Kenzie) and the funding from the NIH and the MJ Murdock Charitable Trust for my lab, we were able to use zebrafish to show that the BMP-related protein, Gdf6a, antagonizes RA pathway activity, balancing proliferation and differentiation as the developing eye grows. Building on this work, we aim to provide cellular and molecular level insight into the mechanisms that (1) enable RA pathway activity to promote cell cycle exit and differentiation in the developing retina and (2) elucidate how Gdf6a controls gene expression and antagonizes RA-pathway activity.