In vitro and in vivo analysis of SPTL cells. (A) Matrigel® culture of SPTL cells. After culturing for six days in 2% serum, SPTL cells were subjected to Matrigel® culture for 16 days, which were then used for hematoxylin and eosin (H&E) staining. (B) Co-immunofluorescence analysis of orthotopically injected SPTL cells for GFP, NKX2-1, and DAPI. The analysis was carried out 14 days after injection of cells. (C) Co-immunofluorescence analysis of intravenously injected SPTL cells for GFP, NKX2-1, and DAPI. The analysis was carried out 28 days after injection of cells. Representative GFP and NKX2-1 co-expressing cells are indicated by arrows in the Merge panel.