Effect of Shp2 inhibitor NSC-87877 on AChR micro-cluster formation. Cultured Xenopus muscle cells, used here and in all experiments described below, were labeled with R-BTX and then incubated overnight in control culture medium (A, B) or in medium containing 1 μM NSC-87877 (NSC) (C, D). Large pre-patterned AChR clusters, often >10 μm in width, were detected in both control and NSC-treated cells (B, D; large arrows), but in cells exposed to NSC, AChR micro-clusters were also frequently observed (D; small arrows). E. Quantification of pooled data from multiple experiments revealed that AChR micro-clusters developed in nearly twice the number of muscle cells incubated in 1 μM NSC-87877 as those maintained in control medium. Mean and SEM values are shown here and in all following figures; control cells, n = 103; NSC-treated cells, n = 109; t-test *p < 0.005.