Dose-dependent inhibition of HUVEC capillary tube formation by gliotoxin. Gliotoxin inhibited angiogenesis in vitro at concentrations similar to those found in the lungs during invasive pulmonary aspergillosis. Specifically, angiogenesis was inhibited by gliotoxin at (A) 3000 ng/mL, and to a lesser extent (B) 300 ng/mL. Gliotoxin at a concentration of 30 ng/mL had no effect on angiogenesis (C,E). (D) Angiogenesis in a control well. **P < .001; *P < .05. P values refer to the comparison with control wells.