KRAS and colorectal adenocarcinoma: Although the above mentioned three KRAS mutant alleles have become established targets for the CRISPR/Cas9 genome- editing system, the G12S mutation, with rectal adenocarcinoma, colorectal adenocarcinoma, and colorectal carcinoma having greater prevalence than the other cancer types (Table 1) 26, has not yet been targeted by the CRISPR system.