TGFB1 and pulmonary fibrosis: PDE is suggested to contribute to pulmonary fibrosis, and there is a report stating that the PDE4B inhibitor suppress pulmonary fibrosis in mice and HLFs from patients with idiopathic pulmonary fibrosis (IPF) by inhibiting the TGFβ signaling pathway and suppressing cell proliferation via IL-1β [41].