Figure 2.

Impaired dimerisation, recycling and activation of transmembrane receptors. (A) HER2-EGFR dimerisation of SKBR3 cells treated for 72 h with soraphen A was determined by proximity ligation assay. (B) Signal intensity, (C) the number of EGFR-HER2 clusters and (D) cluster size were analysed by ImageJ. (E) Receptor recycling of soraphen A-treated and (F) siACC1-transfected SKBR3 cells was monitored by adding rhodamine-tagged transferrin. (G) SKBR3 cells were stimulated with soraphen A for 72 h and phosphorylation of HER2 and EGFR was evaluated by western blot analysis. Prior to lysis cells were stimulated with 100 ng ml⁻¹ EGF for 15 min. Statistical analysis was performed using Student’s t test: n.s. = non-significant, *P<0.05, **P<0.01, ***P<0.001.