MERTK and pulmonary arterial hypertension: We found that MerTK is significantly upregulated in asthma, COPD, pulmonary arterial hypertension, pulmonary fibrosis, and other respiratory system related diseases (as indicated), but is expressed significantly less in allergic rhinitis, allergic rhinitis allergic asthma, rhinitis, systemic scleroderma-interstitial lung disease, and transplanted lung complication (Fig. 5B).