Figure 4. Abundant levels of GSK-3β in adult human pancreatic β-cells. Analysis of GSK-3β levels in β- and α-cells of adult pancreatic tissue sections obtained from donors using immunofluorescence and confocal microscopy. Pancreatic tissue sections were incubated with the specific primary antibodies against insulin, glucagon and GSK-3β followed by incubation with the appropriate secondary antibodies conjugated with either FITC (for insulin) or Dylight (for GSK-β) or TR (for glucagon). In (A), green and red represent insulin and GSK-3β, respectively, and in (B), white and red refer to glucagon and GSK-3β, respectively. In the merge panel, (A), yellow color indicates the levels and localization of GSK-3β in adult β-cell cytosol, whereas, in the merge panel, (B), GSK-3β levels are almost undetectable in α-cells. For (A and B), 10–15 individual islets were assessed each time (n = 4 independent experiments).