IL4 and peripheral arterial disease: Under in vitro hypoxia, which is a plausible reflection of the adverse cellular environment found in ischemic tissue in PAD [53, 90], sensitivity analysis shows that the most influential parameters are closely related to the activation (mostly through direct control of phosphorylation, binding and synthesis) of IFN-γ/STAT1/IRF-1 axis, IL-4/STAT6 axis and O2/HIF-1 axis, as expected (Fig 6A and 6B).