EGFR and lung adenocarcinoma: It is well known that EGFR activating mutations are predominant in lung adenocarcinoma but not in lung squamous cell carcinoma.[39] In our model system, regardless of the cell‐of‐origin, the majority of the transplanted and autochthonous tumors expressed the alveolar type 2 cell marker surfactant protein C. Even EGFR‐activated bronchiolar BASCs, when transplanted, formed mainly alveolar tumors.