KLF4 and idiopathic pulmonary fibrosis: Fibroblasts derived from the lungs of patients with the prototypical fibrotic disease IPF exhibited significantly lower levels of KLF4 mRNA and protein (Figure 1, A and B, and Supplemental Figure 1A; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.160688DS1) than did control patient-derived fibroblasts.