目的 LncRNAs are a large group of poorly characterized non-coding RNAs with ＞200 nucleotides in length.Accumulatingevidence suggests that lncRNAs can play a critical role in regulation of gene expression through various mechanisms.方法 In this study,we performed Knockout of lncRNA PCAT1 by CRISPR/Cas9 technique,and tried to explore the role of PCAT1 inlung cancer.To facilitate the selection of positive clones resulted from CRISPR/Cas9,we generated a donor vector in such a waythat targeting sequence is replaced by marker genes(GFP and PU,the puromycin resistance gene)once it is integrated into thegenomic DNA by homologous recombination.