The present invention provides a method for determining the
intracellular activity of ROCK
kinase comprising, providing a sample of cells to be tested for ROCK
kinase activity, determining the level of
phosphorylation of MYPT1 in the sample, and determining the
intracellular activity of ROCK
kinase in the sample of cells, wherein the level of MYPT1
phosphorylation directly correlates with the level of
intracellular ROCK
kinase activity. The invention further provides a method for identifying an agent that inhibits the intracellular activity of ROCK kinase comprising, providing a sample of cells having ROCK
kinase activity, determining the degree of reduction of
phosphorylation of MYPT1 in the sample by contacting the sample of cells with a
test agent and comparing the MYPT1 phosphorylation level with the phosphorylation level of MYPT1 in an identical
control sample of cells that was not contacted with the
test agent, determining the degree of inhibition of intracellular activity of ROCK kinase in the sample of cells contacted with the agent, wherein the level of MYPT1 phosphorylation directly correlates with the level of intracellular ROCK
kinase activity, and thus determining whether the
test agent is an agent that inhibits the intracellular activity of ROCK kinase. The test agent may for example be a compound not known to have ROCK kinase inhibitory activity, or a compound identified by an
in vitro ROCK kinase
assay as having inhibitory activity.