Rho-associated kinase (ROCK), including the ROCK1 and ROCK2 isoforms, is a protein kinase involved in signaling from Rho to actin cytoskeleton. Many studies on ROCK functions in cultured cells have been reported. However, functions of ROCK in vivo remain incompletely understood, because targeted disruption of the ROCK1 and ROCK2 genes leads to embryonic death. In this study, using a tamoxifen-induced Cre-loxP system, we deleted ROCK1 and ROCK2 in adult mice (ROCK double conditional knockout mice: ROCK DcKO) and explore the in vivo functions of ROCK.
ROCK DcKO mice exhibited poor survival and were observed pulmonary leakage of blood cells after tamoxifen injection. To confirm the increase of vascular permeability in ROCK DcKO, we carried out vascular permeability assay using Evans blue dye. As a result, massive leakage of Evans blue dye was observed in the lung tissue of ROCK DcKO compared with that of control mice. In addition, the number of neutrophils was increased in broncoalveolar lavage fluid (BALF) in ROCK DcKO mice. In the lung tissue of ROCK DcKO mice, the intensity of phalloidin staining and VE-cadherin staining was obviously reduced. These results indicated that pulmonary vascular permeabilities were increased in ROCK DcKO mice.  Furthermore, we found that deletion of ROCKs led to induce the proinflammatory cytokine gene expression through NF-κB and AP-1 by microarray analysis and qPCR. 
Thus, our study suggest ROCK might be involved in maintenance of lung homeostasis though actin cytoskeleton rearrangement.