PDGFRB and idiopathic pulmonary fibrosis: Similarly, several studies had reported that PDGF isoforms and their receptors were upregulated during pathologic fibroproliferative diseases in humans and in murine models by different types of impairment (e.g. radiation- [19,20]/bleomycin- [11] induced fibrosis, idiopathic pulmonary fibrosis [21]) vindicating the importance of the PDGF/PDGFR system in proliferative diseases.