The antibodies used for immunofluorescence were mouse anti-GLUT-1 (NBP1-35926, Novus; used at 1:300 dilution), rabbit anti-CD31 (EPR3094, Abcam; 1:200), and Alexa 488 goat anti-mouse IgG and Alexa 660 goat anti-rabbit IgG (both from Life Technologies; 1:300).