When the other six breast cancer cell lines were exposed to non-hypoxic (20% O2) or hypoxic (1% O2) conditions for 72 h, the percentage of ALDH+ cells was significantly increased under hypoxic conditions in all lines, with the induction ranging from 2.6-fold in T47D cells to 8-fold in MCF-7 cells (Figure 1). The gene discussed is LDHA; the disease is breast cancer.