This vector can silence the expression of 4 target genes simultaneously. Short dsDNA inserts that encode 4 shRNAs are ligated into the insertion sites at each end of the promoters at position 1 (Mlu I/Spe I), 2 (Bgl II/Not I0, 3 (Xho I/ BamH I) and 4 (BsrGI/AscI). The dsDNA inserts are constructed by annealing complementary synthetic oligonucleotides. Each oligonucleotide is designed with a 4-base overhang at its 5’-end. The overhangs complement corresponding restriction sequences in the vector. The neomycin resistance marker facilitates the creation of stable cell lines. The plasmid also contains essential left end sequences of the adenoviral genome and other features that may be used to construct an adenovirus vector using the SpeAd procedure(see Kit #K2400).

This vector may be especially useful when no validation procedure is available. Insertion of 4 different shRNAi sequences that all target the same gene will greatly enhance the probability of achieving effective silencing. Also it is useful to silence several genes at once to block redundant signaling pathways or target genes of the same pathway in a tandem fashion to achieve maximal pathway shutdown.