The methods for evaluating internalization pathways of cellular CPP-mediated ON delivery utilizing a pre-mRNA splice correction assay and fluorescence-based quantification are described. Examples for characterization of CPP uptake routes, employing various endocytosis inhibitors, and special treatment conditions are demonstrated. The methods are developed to characterize cellular delivery of pre-mRNA splice switching peptide nucleic acids conjugated to CPPs by disulfide bond.
