Zeocin is a member of bleomycin family and acts by intercalating DNA causing DNA to cleavage and resulting in cell death. Sh ble gene codes a 13665 Dalton protein in order for the cell to be Zeocin resistant. This protein can be synthesized on the antibiotic which prevents itself from binding to DNA and therefore, has resistance to Zeocin®. Zeocin® is effective for most aerobic cells and can also be used for screening mammalian cell lines, yeast and bacteria. Each type of cell screening requires different amount of Zeocin