Selective reduction of NRP1 by G18 is temperature-dependent. (A) Effects of G18 on levels of cell-surface NRP1, NRP2, VEGFR-2, VEGFR1, gp130, CD31, and SREC-I detected by flow cytometry. HUVECs were incubated at 37°C for 1 hour with or without G18 (16 μg/mL). Shaded graphs reflect control staining. (B) Temperature- and time-dependent reduction of cell-surface NRP1 by G18. HUVECs were incubated with G18 (16 μg/mL) at 4° or 37°C for 5, 15, 30, and 60 minutes. The results reflect the relative mean fluorescence intensities of NRP1 under the conditions of testing. (C) Levels of cell-surface NRP1 detected by flow cytometry on HUVECs incubated with sG18 (0, 1, 2, 4, 8, or 16 μg/mL) in the presence of 1% FBS or with sG18 (0, 4, 8, 16, 32, or 64 μg/mL) in the presence of 95% FBS.