TGFB1 and idiopathic pulmonary fibrosis: Surprisingly, we also found that NEN blocked the cell cycle in the G1 phase (Figure 4H) by negatively regulating cyclin/CDK complexes (cyclin A/CDK2 and cyclin D1/CDK4) in both TGF-β1-induced A549 cells (Figure 4G and Supplementary Figure S2F) and DHLF-IPF cells (Figure 4I and Supplementary Figure S2G).