JAK2 and pulmonary fibrosis: Daily intraperitoneal administration of JSI-124 (1 mg/kg) from day 14 to 28 reduced JAK2 and STAT3 phosphorylation (Fig. 5) as well as the increased protein levels and cell numbers in BAL, lung mass and protein, and expression of IL-6 and IL-13 secondary to lung fibrosis (Fig. 6a–g).