 Lastly, the candidates are spaced to have 1 hairpin in the 3' untranslated region and 4 in the coding sequence.Selected hairpins are cloned into the vector pLKO1, which is a multipurpose plasmid that can be propagated in bacteria, transfected into mammalian cell lines or used for generation of lentiviruses.It contains resistance genes against ampicillin and puromycin.