What is control ShRNA - (Apr/25/2008 )

I understand that the non-targeting shRNA vector is a useful negative control that will activate RISC and the RNAi pathway, but does not target any human or mouse genes. But what sequence does the shRNA in the vector encode. How is it different from just an empty vector.

I'm reading a paper which has shRNA targetting DICER1, Drosha and DGCR8. And these authors infected vectors containing shRNA Drosha, shRNA DGCr8 and shRNA dicer1 into a cell line. And as controls they had infced the cell lines with empty vector and control shRNA. S, what sequence does the vector with control shRNA have?
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paper: impaired microRNA processing enhances cellular tranformtion and tumorigenesis. natue genetics 2008

Thanks
SF

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The sequence of the control shRNA is: 5’-CTTACAATCAGACTGGCGA-3’. I didn't read the entire paper, and the author did not explicitly state this, but I think that the sequence is just scrambled sequence not meant to do anything. Ie, it is a hairpin that doesn't target. It looks like just another (maybe unnecessary) negative control.

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