Lastly, interrogation of The Cancer Genome Atlas (TCGA) reverse-phase protein array (RPPA) cohort29 revealed that HER3 is associated with poor outcome at the later stage of BC with respect to both relapse-free survival (P = 0.0046) and overall survival (P = 0.0074; Fig. 3l and Extended Data Fig. 8). This evidence concerns the gene ERBB3 and breast cancer.