Recent data on mechanisms and applications of transfection strategies by cell penetrating peptides (CPP) are summarized on the variety of different oligonucleotide cargoes including plasmid, antisense and siRNA oligonucleotides. Introduction of PepFect and NickFect technologies for oligonucleotide transfection by transportan-based cellpenetrating peptides in vitro and in vivo is described. 403. Kurrikoff,K., Gestin,M., and Langel,Ü. (2016) Recent in vivo advances in cell-penetrating peptide-assisted drug delivery. Expert Opinion on Drug Delivery, 13(3), 373-387. Takeaway Notes •CPP technology for ON transfection, efficient ON transfection in vitro and in vivo, mechanisms of CPP transfection.