CCN4 and idiopathic pulmonary fibrosis: Moreover, the expression of WNT1-inducible signaling protein-1 (WISP-1), a member of the CCN family of secreted cysteine-rich matricellular proteins and a direct target gene of WNT signaling, is increased in patients with idiopathic pulmonary fibrosis (IPF) and contributes to disease pathogenesis [41].