Here, we have examined the activity of the SARE in anoxic, hypoxic and normoxic conditions in two human breast cancer cell lines, and compared its inducibility to that of three well-characterised HREs from promoters of the human erythropoietin (EPO), human aldolase (ALD) and murine phosphoglycerate kinase 1 (PGK-1) genes. The gene discussed is EPO; the disease is breast cancer.