Figure 1.

Hypoxia-responsive BCD expression and 5-FC sensitivity. (A) Schematic diagrams of the EFp-BCD gene constitutively expressing the BCD (top) and the 5HREp-BCD gene hypoxia-dependently expressing the BCD (bottom). The BCD coding gene was fused to the myc epitope in frame. (B) Western blot analysis of BCD-myc expression in HeLa/EFp-BCD cells or HeLa/5HREp-BCD cells under normoxic (N) or hypoxic (H) conditions. (C and D) Cell proliferation assay of HeLa/5HREp-BCD cells (C) and HeLa/EFp-BCD cells (D). The cells were treated with various concentrations of 5-FC under normoxic (open) or hypoxic (solid) conditions. Cell viability was calculated as the ratio of the absorbance value in each of the conditions against that in medium with 0.001 mg ml⁻¹ of 5-FC under normoxic conditions. Results are the mean±s.d. (n=3). ^*P<0.05. ^**P<0.01.