KRAS and lung cancer: Previous reports indicate that haploinsufficiency for Nkx2-1 promotes development of KRAS-induced mucinous lung adenocarcinoma,30 and that re-expressed Nkx2-1 constrains progression and metastasis of poorly differentiated (NKX2-1 negative) KrasLSL-G12D/+;p53flox/flox lung cancer cells.31