An in vitro method for integrating an exogenous DNA sequence into the genome of a cell using a transposon system. The transposon system includes a first vector carrying inverted repeat sequences and an exogenous DNA, and a second vector that expresses a transposase. Also provided is a kit including the transposon system for integrating an exogenous DNA into the genome of a cell. A method for treating a subject is described that includes engineering an immune cell to carry an exogenous DNA sequence using the method and/or the kit described above and administering an effective amount of the engineered immune cell to the subject.