1.2 CRISPR Cas9 screening
Currently, three different categories of functional gene screening libraries are offered: cDNA libraries, RNA interference libraries, and CRISPR Cas9 gene editing libraries. The latter is further classified into CRISPR-Cas9 knockout libraries, CRISPR-dCas9 activation libraries, and CRISPR-dCas9 interference libraries 17, with the gene-scale CRISPR-Cas9 knockout (GeCKO) 18 being the most prevalent CRISPR library screen. As shown in Figure 1, GeCKO accomplishes this through a series of processes to achieve the screening of genes 19 and drug sites of action18and the identification of the mechanism of action of various impact factors20.