Abstract
This protocol aims to introduce methods for immunostaining two endogenous proteins insulin and glucagon and one exogenous transgene driven EGFP in mouse pancreatic islet. The immunostaining results of insulin and glucagon indirectly tell functionality of pancreatic beta cells and alpha cells respectively. Furthermore, the protocol provides immunostaining steps for the third protein which can be applicable to any other endogenous proteins with a specific antibody generated in mouse.