In the HR-negative cell line MDA-MB-231, WSB-1 knockdown was associated with significantly decreased expression of VEGFA and HK2. Furthermore, WSB1 expression in patient samples did not correlate with several HIF targets including HK2, SLC2A1, and CA9 in breast cancer patient samples, unlike that shown in other tumour types.9,13 This further indicates that the role of WSB-1 in breast cancer HR-negative cells might not be fully dependent on HIF activity, and that other transcription factors are potentially involved. The gene discussed is CA9; the disease is breast cancer.