“…Endodermal markers, such as GATA4, GATA6, SOX17, NODAL, and FOXA2 were upregulated early during endodermal differentiation, with retained expression of GATA6 and FOXA2 in day 15 and day 28 NKX2-1 GFP+ cells. In contrast, the transcripts NKX2-1, SFTA3, SOX9, and FOXP family members were low or absent prior to day 6, and their clear emergence in the day 15 GFP + population is consistent with their published expression during the early lung progenitor period in mouse lung development (35,36). These findings, together with the lack of mature lung marker gene expression in day 15 GFP + cells (low SCGB1A1, SCGB3A2, TP63, SFTPB, and SFTPC), further suggest the day 15 GFP + population represents a relatively undifferentiated or primordial lung progenitor population, as has been observed in early NKX2-1 + progenitors in developing mouse cells in vivo (28).…”