Finally, staining of tissue sections from COPD patients showed the presence of ROCK1 expressing fibroblasts-like cells in small airways and in alveolar parenchyma which suggests that the observed alterations may be relevant in vivo. We suggest that, in the COPD lung, factors in the deteriorating environment trigger differentiation of fibroblasts into a contractile phenotype. Here, ROCK1 is linked to chronic obstructive pulmonary disease.