a. Effect of hypoxia and normoxia on the protein expression of HMGA2 by Western blot. SCC-4, SCC-9 and SCC-10B cell lines were grown under normoxic and hypoxic conditions (1% O2), harvested and the levels of HMGA2 assayed by Western blot, as described in Methods. b. Effect of HMGA2 small interfering RNA on cell viability following doxorubicin treatment in SCC cell lines. The SCC-4 cell line grown under normoxic conditions was transfected with oligonucleotide encoding HMGA2 small interfering RNA or a scramble siRNA sequence. The dose dependent effects of doxorubicin on cell viability was measured by MTT assays. The differences between control cell line and cell lines treated with HMGA2 siRNA was statistically significant (p ≤ 0.01) as determined by Student's t test. The panel below depicts the effects of HMGA2 siRNA and the scramble counterpart on HMGA2 in Western blot. Similar results were obtained for SCC-9 and SCC-10B cell lines. The error bars represent the S.E.M. for 3 experiments.