KRAS and cancer: Next, we tested whether AAV-K could also be used to efficiently edit Kras in precancerous cells that had already suffered other oncogenic alterations, for two reasons: (i) We wanted to ascertain that our vector system could also efficiently edit genes in precancerous cells, since the initial report of poor Kras editing by Platt et al. (15) came from experiments in cells that gained other oncogenic drivers that drove tumorigenesis; and (ii) proto-oncogenes are often activated as secondary or tertiary oncogenic events in atypical cells to accelerate the progression to cancer.