For this purpose, primary fibroblasts isolated from IPF patients were cultured in either pre-fibrotic 3D collagen-I gels or fibrotic 2D collagen-I coated PAA gels as described in Figure 1, and their responses to TGF-β1 were compared to those observed in fibroblasts from control pulmonary tissue. Here, TGFB1 is linked to idiopathic pulmonary fibrosis.