Protein levels of HER signaling pathway members and STAT3 in tumor tissues showed a synergistic decrease in EGFR, HER2 and STAT3, and the activation of HER3 and downstream signaling effectors Akt and ERK was abrogated by joint treatment in both SKBR3 and SKBR3-L xenografts. The gene discussed is ERBB2; the disease is neoplasm.