Fig. 1

Quantitative analysis of collagen gel contraction in the co-culture model stimulated with TGF-β1. a Images of the air-liquid interface co-culture models stimulated with TGF-β1 on culture day 21. The edge of the cell culture insert (red line) and the edge of the collagen gel matrices (red dotted line) are shown in the images on the second row. Arrowheads indicate gaps between collagen gel and the wall of the cell culture insert. b Quantification of collagen gel contraction. Images were obtained on culture days 0, 7, 14, and 21; collagen gel contraction was quantified. The results represent the percentage of the initial gel size. Data are shown as means ± SD of triplicate inserts. *p < 0.05 (Dunnett’s test against the control at each time point). ND, not detected