Localization of VEGFR-2 and NRP-1 in HUVECs. (A-D) HUVECs were stimulated with VEGF-A₁₆₅a for 30 minutes and then stained for VEGFR-2, NRP-1, and the indicated Rab GTPase. VEGFR-2 and NRP-1 colocalized with Rab5, Rab4, Rab7, and Rab11 (arrows). (E) When the cells were stimulated with VEGF-A₁₆₅b, no colocalization of VEGFR-2 with Rab11 was found whereas NRP-1 was still able to traffic through the Rab11 compartment (circles). Arrowheads indicate vesicles positive for NRP-1 and VEGFR-2. Scale bar: 20 μm (insets: 5 μm).