In this context, in this study we developed a conditional Mmp14 null mouse specific for type2 alveolar epithelial cells (AEC2) to evaluate the role of this membrane-type MMP (MT1-MMP) in experimental lung fibrosis as well as gain- and loss-of-function experiments with A549 epithelial cells to unravel possible mechanisms. This evidence concerns the gene MMP14 and pulmonary fibrosis.