There is complex bidirectional crosstalk between HER2 and the signaling pathways activated by hormonal receptors for estrogen (ER), progesterone (PgR), and androgens (AR) that can lead to cancer resistance to either antihormonal drugs [143] or anti-HER2 agents, and thus, co-targeting HER2 and HRs could lead to tumor regression [144]. The gene discussed is ERBB2; the disease is cancer.