BASCs are characterized by their specific location at bronchiolar–alveolar duct junctions and by the expression of both a Clara cell-specific marker (CC10, also known as SCGB1A1 or CCSP) and an AT2 cell-specific marker (SP-C).11 All types of progenitor cells can develop into lung adenocarcinoma in an oncogenic K-Ras-induced mouse lung cancer model24, 29, 30, 31(Figure 2b). Here, KRAS is linked to lung cancer.