KRAS and lung cancer: Previously, we and others demonstrated that Kras lung cancer mouse models with reduced expression of Nkx2‐1 (KrasG12D; Nkx2‐1+/− or KrasG12D; Nkx2‐1flox/flox) developed mucinous lung tumors mimicking human IMA (Maeda et al, 2012; Snyder et al, 2013).