ERBB2 and breast cancer: In addition to TCGA data, to show the variability of the expression of βArr1 or βArr2 in the most aggressive breast cancer cell lines, TNBC cells (MDA-MB-231 and MDA-MB-468) and the less aggressive ones Her2-enriched (SKBR3) and Luminal B (BT474), Western-blot analysis was performed (Fig. 2).