Semiquantitative RT-PCR analysis revealed that HIF-1α was evenly expressed at an oxygen concentration of 0.1% O2 for up to 24 h of hypoxia and continued a stable expression upon reoxygenation up to 20 h after 24 hours of hypoxia in Hep-1-6, Hep-3-B and HepG2 (Fig. 2A) as well as in (A-549), HT-29 and HCT-116 colon cancer cell lines (Fig. 2C), where there is no up-regulation of HIF-1α mRNA in the cell lines examined. The gene discussed is HIF1A; the disease is malignant colon neoplasm.