(Figure ). This shows the dissociation of lipids from nanogels followed by the loss of fluorescent signal of FITCliposome probably due to "dilution" of lipids in the cell lipidic environment following a probable lipid exchange occurring during FITC-LPX-633 cell internalization. Indeed, during internalization of nucleic acid vectorized by cationic liposomes, it is known that a lipid exchange occurs with endosomal membrane inducing disruption of endosomal membrane and delivery of nucleic acid in cytoplasm. In order to provide evidence of endosomal escape of our DNA-protein NG inside cells, we performed immunolabeling of endosomes and lysosomes in cells after delivery of lipoproplexes. For this purpose, anti-EEA1 and anti-LAMP1 antibodies were used for immunostaining of early endosomes and lysosomes, respectively. After 2 hours of incubation of cells with fluorescent LPX (in this experiment, we used AlexaFluor555 streptavidin for nanogel formation, resulting in LPX-555 to allow multichannel observation of nanogels, cell nuclei and immunolabeling), we observed only rare events of colocalization of NG with EEA1 (Figures and). Interestingly, in the most cases the nanogels were found close to endosomal compartments. We thus hypothesize that this observation was performed after endosomal escape. Concerning lysosomes, we observed no colocalization of NG with LAMP1 labelled compartments (Figure ).The endosomallysosomal system is a dynamic process where intracellular membranous compartment interconvert from early endosome, that maturate to late endosomes and then fused into lysosomes. As lysosome appears to be the "last" part of this pathway, we can assume that if NG are rarely observed inside early endosomes, it is expected that NG inside lysosome may be even more rare or even impossible to observe.