NKX2-1 and lung carcinoma: Observations of a much more widespread proliferative response comprising both CC10+ bronchiolar and SPC+ alveolar cells already 10 days after induced activation with tamoxifen (Figures S8A–S8C) further argued that lung cancer development in non-induced Nkx2.1-CreERT2;BrafCA/+ mice predominantly derived from AT2 cells.