TGFB1 and idiopathic pulmonary fibrosis: In the non-canonical (SMAD-independent) activation pathways, tyrosine-protein kinase ABL1 [56], Janus kinases (JAK) [57,58], PI3K [52,59], and mitogen-activated protein kinases (MAPKs) [60] have been shown to be directly activated by TGF-β, mediating persistent activation of fibroblastic cell populations in IPF.