This lecture introduces T-REX, a method to study electrophile signaling in vivo, using targeted reactive electrophiles and oxidants to mimic native signaling. It covers applications in live cells, larval zebrafish, and worms, highlighting the intersection between electrophile signaling, DNA damage response, and RNA synthesis. The lecture also discusses precision electrophile signaling in innate immunity and isoform-specific drug development, showcasing the potential for novel target discovery and drug design.