Fig. 8. Inhibition of ROCK impairs laminin-induced AChR clustering. To determine the contribution of ROCK to AChR clustering, the ROCK inhibitor Y27632 was added to differentiated C2 muscle cell cultures at a concentration of 20 µM. One day after treatment, the effect on laminin-induced AChR surface distribution in Y27632-treated and -untreated myotubes was quantitated and compared with the effect of ROCK inhibition on agrin-induced clustering. Inhibition of ROCK activation impaired agrin-induced AChR clustering by more than 80% (b), but only impaired laminin-induced AChR clusters by approximately 40% (d) compared with untreated cells (a,c) (error bars represent ±s.e.m.; n=100 cells from five or more separate platings).