(A) Perturbation of the S-TSHR-mAb–induced formation of early endosomes (red) by the G protein disruptors suramin, hydrobromide (HyBr), and Antag3. Note that Baf-A1 and guanosine diphosphate (GDP) induced malformed EE formation. Antibodies are labeled in green. Scale bar, 100 μm. Images are representative of three independent experiments. (B) Quantification of the images represented in (A) was performed by measuring the FI of red EE-spots (R-EE-spots), R-FI-EE, green mAb-spots (G-mAb-spots), G-Fl mAb-spots, and colocalization. Data are means ± SEM of three experiments with at least three images analyzed per experiment. *P < 0.003 compared to S-mAb.