ERBB2 and breast carcinoma: In line with these results, we found that SorLA-, HER2- and HER3-containing BiFC dimers reside in Rab4-positive intracellular compartments in BT-474 cells (Fig. 5E, F), further highlighting the Rab4 pathway in mediating SorLA regulation of HER2-HER3 complexes in breast cancer.