We examined serial sections of human H460 lung adenocarcinoma xenograft tumors resected from athymic mice for expression of PFKFB4 and PFKFB3 and correlated the expression levels of these proteins using carbonic anhydrase IX, a potent transcriptional target of HIF-1α, as a hypoxia marker. This evidence concerns the gene CA9 and lung adenocarcinoma.