NF1 and neoplasm: Twenty weeks after intratracheal infection of KP mice with lentiviral vectors expressing sgRNAs against Nf1 (sgNf1.1, sgNf1.2, and sgNf1.3) or tdTomato (sgTom) as control, we observed significant increases in average and total tumor volume in KP mice infected with sgRNAs against Nf1 as compared to sgTom (Fig 1B and C).