Preventive effect of regorafenib on development of PPE-induced emphysema in mice. (A) Experimental scheme. In the PPE + regorafenib (Reg) group, regorafenib (5 mg/kg) was administered orally for one day for sensitization before and consecutive seven days after treatment with PPE via the intranasal route. At three weeks after treatment with PPE, mice were analyzed to measurement of Lm and lung function. (B) Representative H&E stained images. Scale bar indicates 100 μm. (C) Quantification of Lm. N = 6/group. (D) Lung function test. Cst (static compliance), A (total lung capacity) and K (form of deflating the PV-loop) parameters are shown. N = 6/group. Error bars indicate the mean ± SEM. *P < 0.05, **P < 0.01, ****P < 0.0001, t-test.