FOXA1 and lung adenocarcinoma: To test the hypothesis that FoxA1/2 are required for lung adenocarcinoma cells to undergo a pulmonary to gastric lineage switch upon loss of NKX2-1 expression, we incorporated conditional alleles of Foxa1 and Foxa2 into a mouse model of NKX2-1-deficient lung adenocarcinoma (Snyder et al., 2013).