CRISPR-Cas9 technology is a highly efficient gene-editing tool essential for exploring gene function in functional genomics. The GeCKO v2 library, developed by Feng Zhang's team and available through Addgene (IDs: #1000000048, #1000000049), includes 123,411 gRNAs targeting about 19,050 human genes. This resource enables high-throughput screens to identify critical genes in biological processes or diseases by effectively disrupting target genes. Its precision makes CRISPR ideal for studying complex genetic networks, especially in cancer research.