CDK1 and colorectal carcinoma: We then generated stable Cas9-expressing clones of the CRC line DLD1 (see Methods) and confirmed that each line (hereafter, LC9) could induce rapid depletion of sgRNAs targeting essential genes (e.g. CDK1 or RPA3)[22]; We chose the three most efficient clones as replicates for the screen (S2A Fig).