The gene encoding CA9 conforms to a pattern first described among genes encoding glycolytic enzymes (Hu et al, 2003), and is specifically responsive to HIF-1α, showing no response to HIF-2α in any cell type, whether non-RCC or RCC (Grabmaier et al, 2004; Raval et al, 2005). The gene discussed is HIF1A; the disease is renal cell carcinoma.