KRAS and lung adenocarcinoma: In addition, this approach can be expanded to other mouse carcinogen models, such as methyl-nitrosourea (MNU) which leads to a preferred G12D Kras mutation in lung adenocarcinoma, or mouse squamous lung cancer using N-nitroso-tris-(2-chloroethyl)urea (NTCU) where Tp53, Pten, Cdkn2, and Lkb1 deletion and/or mutation are potential key drivers [22].