Figure 6.

Staurosporine and herbimycin inhibit AChR and phosphotyrosine cluster formation, but not binding and distribution of laminin-1 on myotube surfaces. (A) C2 myotubes were treated with 120 nM laminin-1 for 7 h in the presence of 10 nM staurosporine or 1 μM herbimycin and triple stained for AChRs, phosphotyrosine, and laminin. AChRs were visualized with rhodamine-α-btx; phosphotyrosine and laminin-1 were visualized with primary antisera followed by FITC- and Alexa350-conjugated secondary antibodies, respectively. Bar, 20 μm. (B) Total AChR clusters or three subgroups of AChR clusters (size, 5–10 μm, 10–30 μm, and >30 μm) were analyzed after treatment with laminin-1 alone or together with 10 nM staurosporine or 1 μM herbimycin. Both inhibitors prevent formation of laminin-induced AChR clusters of all sizes. Data represent mean ± SD of at least three experiments.