Intended use:Novel mechanism of gene amplification discovered in cancer cell studies.Protein expression system in mammalian cells has the great advantage to produce mammalian protein representing proper three-dimensional conformation as well as modifications after translation. The structure found in mature protein is essential in the process of proteomics study and protein engineering. However, levels of protein expression in mammalian cells are relatively low in comparison with the other expression systems using bacteria or insect cells, so that the lower expression levels make difficulties in further application. In order to obtain a high-producer mammalian cell line, multiple copies of an expression vector might be introduced into a host cell. IR/MAR gene amplification is a technology based on a novel mechanism of gene amplification discovered in cancer cell studies. A DNA fragment containing IR (Initiation Region) and MAR (Matrix Attachment Region) effectively amplifies the copy number of a co-transfected expression vector, leading to high protein production rate. Stable cell lines with high protein expression can be easily obtained by standard transfection methods and drug selection.