SPARC and idiopathic pulmonary fibrosis: SPARC (secreted protein acidic rich in cysteine), an extracellular matrix component abundant in fibroblastic foci [33], should also be noted, as it has been shown to activate AKT, inhibit GSK-3β, and activate β-catenin, resulting in an anti-apoptotic phenotype [34], another characteristic of the IPF myofibroblast.