The pIRES selection vectors pIRESpuro3, pIREShyg3, pIRESneo3, and pIRESbleo3 each contain a multiple cloning site located upstream of a selection marker expressing IRES. Because your gene of interest and a selection marker are translated from a single RNA, you can be confident that nearly 100% of the colonies resistant to puromycin, hygromycin, G418, or bleomycin also express your protein of interest. All IRES selection vectors contain a partially disabled IRES which reduces the efficiency of translation initiation for the selection marker relative to that of the cloned gene and allows preferential selection of cells expressing high levels of your protein of interest. The pBApo series of vectors are mammalian expression vectors for constitutive expression of your gene of interest from either a CMV or EF1-alpha promoter. The antibiotic resistance marker, either puromycin or neomycin, is expressed separately from an SV40 promoter. pBApo-CMV lacks a selectable marker.