Expression of short hairpin RNA (shRNA) targeting HIF-1α in triple-negative SUM159 or human epidermal growth factor receptor 2-positive (HER2+) HCC1954 breast cancer cells blocked the hypoxic induction of PLXNB3 mRNA and protein, whereas expression of shRNA targeting HIF-2α had no effect. The gene discussed is HIF1A; the disease is breast cancer.