(52) found that HER2 can also up-regulate AGR2 by activating the extracellular signal regulated kinase 1/2 (ERK1/2) - Akt pathway, leading to the proliferation of breast cancer cells, indicating that in estrogen receptor negative breast cancer, AGR2 expression level is significantly correlated with HER2 expression status. The gene discussed is ERBB2; the disease is breast carcinoma.