Effect of NE in vitro (with or without sunitinib). VEGF, IL-8 and IL-6 protein levels in culture supernatants by A549 (A, B, and C) and B16F1 (D, E and F) cells were measured after incubation with 0 (CON), 0.1, 1, 10 μM NE and 10 μM NE + 10 μM PROP for 3, 6, 12 and 24 hours. The levels of VEGF, IL-8, and IL-6 protein in B16F1 (G, H and I) cells incubated with 3.35 μM SUN alone (CON), 3.35 μM SUN + 10 μM NE, 3.35 μM SUN + 10 μM PROP and 3.35 μM SUN + 10 μM NE + 10 μM PROP for 6 hours were also detected. Data are represented as percentage of the control well, which was set as 100% in each experimental series. All bars represent the mean ± SD of at least three experiments performed in duplicate. CON, control. SUN, sunitinib. ND, not detectable. *, P ≤ 0.05; **, P ≤ 0.001.