the modification of the three 5 ' ccgg 3 ' sequences at nucleotides +24 , +6 and -215 , relative to the cap site in this promoter , sufficed to silence the gene in transient expression either in xenopus laevis oocytes or in mammalian cells , and after the fixation of the e2a promoter-chloramphenicol-acetyltransferase ( cat ) gene construct in the genome of hamster cells .
C0086860
chloramphenicol-acetyltransferase
C0007634
cells