Our experiments have demonstrated, for the first time, that MI-2, a MALT-1 inhibitor, can protect from bleomycin-induced pulmonary fibrosis based on the the following results: MI-2 reduced lung damage, pulmonary edema, inflammatory cells infiltration in both bronchoalveolar lavage fluid and lung tissues, cytokines over-expression, production of free oxygen radicals, collagen deposition, fibrosis, changes in α-sma, an EMT related gene, and TGF-β expression. Here, TGFB1 is linked to pulmonary fibrosis.