Description: The pCI-neo Mammalian Expression Vector carries the human cytomegalovirus (CMV) immediate-early enhancer/promoter region to promote constitutive expression of cloned DNA inserts in mammalian cells. This vector also contains the neomycin phosphotransferase gene, a selectable marker for mammalian cells. The pCI-neo Vector can be used for transient or stable expression by selecting transfected cells with the antibiotic G-418. (1)Strong, Constitutive Expression: The human cytomegalovirus (CMV) immediate-early enhancer/promoter region produces strong, constitutive expression. A β-globin/IgG chimeric intron located downstream from the enhancer/promoter region can further increase expression. The vector is maintained as an episome in cells expressing the SV40 large T antigen, leading to even higher levels of expression. (2)Transient or Stable Expression: The neomycin phosphotransferase gene allows selection of stable transfected cells. (3)Increased Steady-State mRNA Levels: The late SV40 polyadenylation signal increases the steady-state level of RNA approximately fivefold more than the early SV40 polyadenylation signal. (4)Convenient: Multiple cloning sites exist for easy insertion of cDNA. (5)Versatile: Synthesize transcripts in vitro using the T7 RNA polymerase promoter or generate single-stranded DNA in E. coli using the f1 origin of replication.