Rho-associated protein kinase (ROCK), downstream effector of Rho GTPases, is a kind of serine-threonine protein kinase. Two mammalian ROCK homologs, ROCK1 and ROCK2, have been identified, which share 92% identity of amino acid sequence in their kinase domain and have a similar structure. In its native state, ROCK is self-suppressed by the pH domain in the carboxyl-terminal region. However, when RhoA and (or) RhoC are activated to bind to the RBD domain or the auto-inhibitory region is cleaved and removed by caspase-3 or Granzyme-B, ROCK is activated. As a well-described signaling cascade transmission, RhoA/ROCK pathway is an inhibitory cue to the growth cone by modulation of actin dynamics. Within this pathway, ROCK has a vital role on inhibitory signals for axon growth and in the regulation of cell survival. Although ROCK is ubiquitously expressed in all tissues, ROCK1 is mainly expressed in non-neuronal tissue and ROCK2 is expressed in brain and the spinal cord abundantly and improves with age.