Puromycin is an aminonucleoside antibiotic produced by Streptomyces alboniger (1). It inhibits the growth of Gram positive bacteria and various animal and insect cells. Fungi and Gram negative are resistant due to the low permeability to the antibiotic. But in some particular conditions puromycin can be used for E. coli selection. For more than 30 years, puromycin has been widely used as a basic tool for studying protein synthesis. Now, puromycin hydrochloride is particularly useful for the selection of cell types harbouring plasmids carrying puromycin resistance genes (2,3).