TGFB1 and idiopathic pulmonary fibrosis: To address this gap of knowledge, we cultured primary pulmonary fibroblasts from control tissues and IPF patients in hydrogels with tunable elasticity in the absence or presence of TGF-β1, and examined the expression of both COL1A1 and two important collagenases that are upregulated in IPF (i.e., MMP1 and MMP2).