Antibody:	anti-Foxa2/HNF3beta
Detection system:	Secondary antibody coupled to Cy2

Structure	Level	Pattern	Image	Note
TS23: pancreas epithelium	Present	Widespread	5A , 5B , 5C	Expressed at lower levels in the cells lining the lumen of the epithelial chords, while high level cells were detected within or adjacent to the epithelial chords. There was a statistically significant correlation between Neurog3 and Foxa2 expression levels (see Fig 5D and 5E).

Structure	Level	Pattern	Image	Note
TS21: pancreas epithelium	Present	Widespread	S3A	Homogeneously expressed throughout the branching pancreatic epithelium, with the exception of a few cells displaying higher levels.

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present	Widespread	S3B	Expressed at lower levels in the cells lining the lumen of the epithelial chords, while high level cells were detected within or adjacent to the epithelial chords.

Structure	Level	Pattern	Image	Note
TS21: pancreas epithelium	Present		S3E , S3C	Cells with higher expression appeared both grouped in clusters or as single cells within or in close proximity to the pancreatic epithelial chords.

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present		S3F , S3D	Expressed at lower levels in the cells lining the lumen of the epithelial chords, while high level cells were detected within or adjacent to the epithelial chords.

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present		S4A	High-level Foxa2 expression cells did not express Sox9. Coexpressed with Sox9 in low-level Foxa2 expression cells.

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present		S4B	Low-level Foxa2 expression cells, lining the epithelial chords, coexpressed Muc1.

Structure	Level	Pattern	Image	Note
TS22: pancreas branching epithelium tip	Present		S4C	No Nkx6-1 expression at these positive tip cells, which mainly contributes to acinar fates.
TS22: pancreas branching epithelium trunk	Present		S4C	Co-expressed with Nkx6-1. Some of the scattered double positive cells were detected adjacent to the epithelial chords, suggestive of cells in an intermediate state of beta-cell differentiation.

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present		S4D	Almost complete overlap between Foxa2 and Pdx1 expression. Most of the Pdx1 highly expressed cells did not display the highest levels of Foxa2.

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present		S4E	Most of the Foxa2 highly expressed cells were Ins1/2 negative (not beta-cells).

Structure	Level	Pattern	Image	Note
TS22: pancreas epithelium	Present		S4F	Almost complete overlap between Foxa2 highly expressed cells and Chga expression, showing their likely specification toward an endocrine fate.