MTOR and pulmonary fibrosis: To investigate the role of mTOR signaling in AECs during the process of pulmonary fibrosis, we obtained transgenic SPC-rtTA/TetO-Cre/TSC1+/f (STT) mice by crossing three types of transgenic mice, SPC-rtTA, TetO-Cre and TSC1f/f, with each other.