TGFB1 and idiopathic pulmonary fibrosis: However, data generated in this study utilizing PCLS from diseased human IPF tissue has compared the effects of GSK3008348 with highly selective αvβ1 (c8) and αvβ5 inhibitors and shown that of these the αvβ6 integrin appears to be the major contributor to TGFβ activation and downstream phosphorylation of Smad2 in this system.