CFTR and cystic fibrosis: Rho kinase has been shown to play a key role in contraction by modulation of Ca influx through L-type Ca channels and through modulation of MLCP activity (Wang et al. 2004).The sustained component of the response to K+ depolarization in cftr−/− is more ROK sensitive than in cftr+/− mice; this result suggests that ROK activity is elevated in the CF airway.