To address this, a library of gRNA sequences targeting protein-coding genes was created, and using colorectal carcinoma (such as KRAS-activated (G13D) mutants DLD1 and HCT116) and other cancer cell lines expressing Cas9, over 5-fold more essential genes were observed when compared to RNAi or previous generation CRISPR screens [35]. The gene discussed is KRAS; the disease is colorectal carcinoma.