TGFB1 and idiopathic pulmonary fibrosis: Fms-like tyrosine kinase-3 ligand (Flt3L), a cytokine that promotes differentiation and proliferation of DCs, was found to be upregulated in the peripheral blood and lungs together with an increase in DCs in the lungs of TGF-β1-induced murine model of PF as well as in IPF patients (167).