The pCI-neo Mammalian Expression Vector(a,b) carries the human cytomegalovirus (CMV) immediate-early enhancer/promoter region(b) to promote constitutive expression of cloned DNA inserts in mammalian cells. The pCI-neo Vector contains the neomycin phosphotransferase gene, a selectable marker for mammalian cells. This vector can be used for transient expression or for stable expression by selecting transfected cells with the antibiotic G-418. The sequences are also available from the GenBank® database (GenBank®/EMBL Accession Number for the pCI-neo Mammalian Expression Vector is U47120).