Transcriptional profiling in zebrafish using optimized photoswitchable MEK PatelAleena YeungEyan McGuireSarah WuAndrew E ToettcherJared Y ShvartsmanStanislav D. BurdineRebecca 2020 An optogenetic tool for activating the ERK signaling pathway in vivo in zebrafish is described. The tool is an optimized version of photoswitchable MEK, which we use to investigate the transcriptional effects of ERK activation during germ layer specification.