In a proof-of-principle experiment, Platt et al. [144] developed an adenovirus-associated vector (AAV) that delivered the guide RNAs to simultaneously knockout Trp53 and Stk11 along with a gRNA and homology-directed repair template to introduce a G12D mutation in Kras. The vector also contains an expression cassette for Cre recombinase, which induces the conditional activation of a Cas9-expressing transgene that is essential for the targeted manipulation of the three cancer-promoting target genes. The gene discussed is KRAS; the disease is cancer.