The CMV immediate-early enhancer/promoter region present in the pTARGET™
Vector allows for strong, constitutive expression in a variety of cell types. The
promiscuous nature of the CMV enhancer/promoter has been demonstrated in
transgenic mice, where expression of the chloramphenicol acetyltransferase
(CAT) gene regulated by the CMV enhancer/promoter was observed in 24 of the
28 tissues examined (5). The pTARGET™ Vector also contains the simian virus
40 (SV40) enhancer and early promoter region upstream of the neomycin phosphotransferase
gene. The SV40 early promoter contains the SV40 origin of replication,
which will induce transient, episomal replication of the pTARGET™ Vector
in cells expressing the SV40 large T antigen such as COS-1 or COS-7 cells (