Immunofluorescence Staining of Pancreatic Markers

Immunofluorescence staining was performed as previously reported^{10 (link)}. The following primary antibodies were used: anti-insulin (dilution 1:100, #4590; Cell Signaling Technology), anti-C-peptide (dilution 1:100, #4593S; Cell Signaling Technology), anti-PDX-1 (dilution 1:200, #5679; Cell Signaling Technology), anti-NKX6.1 (dilution 1:400, #54551; Cell Signaling Technology), anti-ICA (dilution 1:500, ab207750; Abcam plc.), anti-ZnT8 (dilution 1:500, 16169–1-AP, Proteintech, Chicago, IL, USA), anti-GAD65 (dilution 1:50, ab239372, Abcam plc.) and anti-PD-L1 (dilution 1:25, 17952–1-AP, Proteintech). Anti-rabbit Alexa 488 (A-11008; Thermo Fisher Scientific Inc.) for anti-C-peptide, PDX-1, ICA, ZnT8, GAD65 and PD-L1 antibodies, and anti-mouse Alexa 594 (A-11005; Thermo Fisher Scientific Inc.) for anti-insulin antibody were used as the secondary antibodies. 4′, 6-diamidino-2-phenylindole (DAPI) (P-36931; Thermo Fisher Scientific Inc.) was applied for nucleus staining.