This vector can silence the expression of 4 genes simultaneously.?Sequences from the target genes are used to design short cDNAs that are ligated into the insertion sites at each end of the promoters.?The cDNAs are constructed by annealing compementary oligonucleotides to one another.?Each oligonucleotide is designed with a 4-base overhang at its 5'-end.?The overhangs complement vector sequences that remain after digestion with a pair of restriction enzymes that is unique for each insertion site.?The other features of this plasmid facilitate rapid conversion to an adenovirus vector using the SpeAd procedure.?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.