In conclusion, delivery of nucleic acids by cationic liposomes has shown extremely rapid development in the last 5 years. Numerous cell types have been transfected, more than half a dozen commercial liposome kits are on the market, and many laboratories which are not involved in any lipid or liposome research are routinely using such liposomes in their work. The field is still rapidly growing and so is our knowledge of the basic science underlying these transfections, cell function, and gene functionality.