Fuente: WIPO "varroa" The present invention relates to a method for optimizing the production of a RNA sequence of interest in a cell, comprising the steps of a) introducing into a plurality of cells a vector capable of expressing a heterologous RNA of interest, wherein said RNA is tagged with a RNA tag comprising an aptamer capable of stabilizing a fluorophore and a scaffold capable of stabilizing the aptamer; b) culturing the cells in a culture medium under conditions that allow expression of the heterologous RNA of interest; c) adding said fluorophore to the culture medium; and d) identifying those cells that show the highest intensity of fluorescence and therefore a high expression of the RNA of interest.