Levels of lactic acid, a metabolite generated in response to hypoxia, are high in IPF lung tissue supporting the concept of a hypoxic microenvironment (6) and HIF-1α and -2α have been shown, ex vivo, to be expressed in lung biopsies from patients with IPF, in some but not all reports (7, 8). The gene discussed is HIF1A; the disease is idiopathic pulmonary fibrosis.