Northern hybridizations with HIF-1– and VEGF-specific probes on total RNAs from HepG2 cells. Cultures were grown in conventional culture dishes to 20%-30% confluence. Normoxic cells (N) were incubated in 20% O₂ and hypoxic cells (H) in 3% O₂ for 4 hours with TNF 10 ng/mL or IL-1β 300 pg/mL. The ethidium bromide fluorescence of the RNA is shown at the bottom. Neither of the 2 cytokines had an effect on HIF-1 or VEGF mRNA levels after 4 hours of incubation.