Abstract: Provided is an improved method for controlling gene expression in vivo through the use of a gene switch comprising one or more aptamer sequences operably linked to or incorporated into the untranslated regions (UTRs) of a transgene or nucleotide sequence of interest. Also provided are expression vectors having aptamer sequences located within the 3? UTR, the 5? UTR and between the genes of a multicistronic mRNA, as well as methods of using the expression vectors for controlling or regulating gene expression.