Studies have also suggested that while tumor cells adapted to the long-term reactive oxygen species (ROS)-induced toxicity, this promoted acquired multidrug resistance in breast cancer cells through the PI3K/protein kinase B (PI3K/Akt) and NF-ĸB pathways regulated by the stress-related factors, NF-E2-related factor 2 (Nrf2), hypoxia-inducible factor 1, and protein kinase C (11). The gene discussed is NFE2L2; the disease is breast cancer.