Cells were fixed and exposed to specific anti-GLUT1 primary antibody. Bar 15 μm. A: In maintenance medium, GLUT1 demonstrates primarily a plasma membrane distribution as well as some intracellular mostly perinuclear staining. B: After exposure to prolactin-rich medium for 4 days, GLUT1 was specifically targeted intracellularly, demonstrating a perinuclear pattern, as well as a distinct nuclear membrane staining.