Current mRNA therapeutics and vaccines are designed for high and ubiquitously translation. However, for many mRNA drugs and gene therapies the expression of the therapeutic RNA in all cells is undesirable and translational control must be tailored to the target tissue. To engineer cell-type specific mRNA translation this project will use rational design and high-throughput in vivo screening of structured RNA elements. RNA modules that confer cell-type-specific or cancer-specific expression will be identified to incorporate in next-generation mRNA drug designs.