Mechanism of nAChR-mediated angiogenesis. (a) VEGF-neutralizing antibodies, but not bFGF-neutralizing antibodies, partially inhibit nAChR-induced network formation. *P < 0.01 vs. nicotine alone; **P < 0.01 vs. DMXB alone. (b) The nAChRs are partially involved in VEGF-mediated angiogenesis but not in bFGF-mediated angiogenesis. *P < 0.01 vs. VEGF alone. (c) Nicotine dose- and time-dependently stimulates VEGF receptor-2 activation. A representative blot is shown. n = 3. (d) The MAPK (MEK) inhibitor PD98059, the p38 MAPK inhibitor SB203580, the PI3K inhibitor LY294002, and the NF-κB inhibitor PDTC completely inhibited nAChR-induced network formation. Results are shown as box plots displaying 25th and 75th percentiles as boxes and 5th and 95th percentiles as thin lines. *P < 0.01 vs. nicotine alone. n = 4 for each experiment.