STAT3 and idiopathic pulmonary fibrosis: In addition, IL-6 upregulates the expression of pro-apoptotic protein Bax and promotes Fas-induced apoptosis through the STAT-3 signaling pathway in normal fibroblasts, while it induces the expression of anti-apoptotic molecule Bcl-2 and proliferation of IPF fibroblasts by ERK signaling pathway73.