Fig. 1. The 6ß4 integrin is expressed by human dermal microvascular endothelial cells. (A-D) Sections of human neonatal foreskin were double immunostained with antibodies to the endothelial marker von Willebrand Factor (vWF) (A), and with 3E1 antibodies to the ß4 subunit (B). The white dotted line indicates the epidermal-dermal interface. (C) The colocalization of ß4 and vWF is seen in the merged image as yellow, with a representative ß4-positive vessel indicated by the arrow. (D) A microvessel in cross section examined at higher magnification using confocal laser scanning microscopy, showing vWF (green) and ß4 (red). (E-J) Cells isolated from human neonatal foreskin were double immunostained to detect ß4 and endothelial cell-, smooth muscle cell-, and keratinocyte-specific markers: (E) cells stained with pAb to PECAM-1 (red) and 3E1 to ß4 (green); (G) cells stained with 1A4 to smooth muscle actin (red) and 3E1 to ß4 (green); and (I) cells stained with AE1/AE3 to human epidermal keratins (red) to detect keratinocytes and 439-9B to ß4 (green). (E,G,I) The corresponding phase contrast images are shown in F, H and J, respectively. The cells that stained brightly with only ß4 in E and G are probably keratinocytes. Scale bars: (A-C) 50 µm; (D-J) 10 µm.