LPS signals endothelial sprouting through a TRAF6-mediated pathway that activates NF-κB and JNK. Microcarrier beads seeded with endothelial cells were embedded in fibrin gels and exposed to various stimuli. (A) An example of endothelial sprouts (arrows) formed in this assay following LPS (100 ng/mL) stimulation. (B) Quantitation of the number of sprouts formed following stimulation by serum-only (control), bFGF (1 ng/mL), LPS (100 ng/mL), or TNF (10 ng/mL). Effect of inhibiting (C) TRAF6 activation, (D) NF-κB activation, or (E) JNK activation on endothelial sprouting in response to bFGF (1 ng/mL) or LPS (100 ng/mL). Each experiment was done in triplicate, and the total number of experiments done in each case is indicated on the graph. Results shown are the mean + SEM of the total number of experiments. *P ≤ .05, **P ≤ .01.