The invention relates to a system and method for introducing DNA into cells. In particular, the invention relates to a method for introducing single or multiple copies of a DNA sequence or gene of interest into a cell comprising providing: a) a “copy and paste” transposase； and b) a construct comprising a DNA sequence or gene of interest flanked by a “copy and paste” transposon terminal sequence, such as an LTS or RTS. A novel “copy and paste” transposon of the Helitron family is described along with systems for using the corresponding transposase in methods for introducing DNA into cells, for example, to generate cell lines for use in protein production, cell and gene therapy or as reference standards.
