To verify if oxygen plays indeed an important role in the mechanism responsible for prevention of nuclear HIF-1 accumulation by metformin in hypoxic multiple myeloma cells, we established the non-physiological anoxia, meaning almost complete oxygen-deprived culture environment and in this experimental setup we determined the influence of metformin on HIF-1 alpha stabilization. The gene discussed is HIF1A; the disease is plasma cell myeloma.