Cell targeting defines one of the most challenging and important needs in modern medical treatment approaches in order to affect specifically diseased cells while minimizing side effects for healthy cells. We developed selectively expressed RNA (seRNA) molecules that transfer cell targeting for the very first time from the cell surface of diseased cells to their whole intracellular transcriptome. By interaction with any cell type specific RNA out of this transcriptome, seRNAs change their conformation to switch from a formerly inactive molecular pro-drug to its active form, enabling translation. At the same time, lack of activation in healthy cells prevents seRNA induced protein effector formation. Our research aims to further characterize underlying seRNA functional mechanisms and to tune regulatory aspects. At the same time, we are developing seRNA molecules for reseach as well as preclinical and clinical applications against diseases with highest medical need, such as brain tumors (glioblastoma) or Neuronal Ceroid Lipofuscinosis (NCL).