RAC1 and asthma: Recently, evidence from previous studies has shown that the activation of RAC1 induces airway SMC contraction and results in airway hyperresponsiveness associated with asthma (Andre-Gregoire et al. 2018, Kai et al. 2019); additionally, the activation of RAC1 regulates the vascular SMC contraction involved in the pathogenesis of hypertension (André et al. 2014).