RAC1 and asthma: To examine the effect of S1P on RAC1 in the airways, RAC1 expression in lung pathological tissue sections was examined using immunohistochemistry, which showed that JTE-013 significantly reduced the positive expression of RAC1 in lung tissues during the inflammatory phase of asthma (Supplementary Figure S1A) and airway remodeling (Supplementary Figure S1B).