In addition to attenuated fibrosis, we found that the accumulation of α-SMA positive cells around the small airways was significantly reduced in SphK2−/− mice compared with those in WT mice (Figure 2D and 2E), suggesting that SphK2 deficiency attenuated the pathological fibrotic and emphysema manifestations in mice with chronic CS exposure. Here, ACTA1 is linked to pulmonary emphysema.