Our final aim was to explore evidence for a direct functional link between PI3K/mTOR signalling and matrix formation in this disease setting by monitoring the release of the human pro-collagen 1 amino-terminal peptide (P1NP) in IPF tissue slices using a competitive ELISA based on a proprietary monoclonal antibody.25, Figure 8D shows that the related GSK2126458 analogue, Compound 1, reduced P1NP levels released into lung slice supernatants, with maximal inhibition observed at >100 nM; the effect of a Alk5 inhibitor, SB525334 (10 μM), is also shown. This evidence concerns the gene TGFBR1 and idiopathic pulmonary fibrosis.