Immunofluorescence...        to detect specific proteins -                 one may use antibodies to a specific protein tagged with fluorescent molecules, such as ...     (fluorescein = yellow/green) which will bind to protein antigens in the tissue & fluoresce. This picture is of rat intestine tagged with fluorescein fluorescing antibody for a GLUT 2, a protein involved in glucose transport. The GLUT2 is present in the BASAL & LATERAL membrane sides of the epithelial cells, but not in brush border area.