Since glucocorticoids increase ROS generation in metastatic B16-F10 melanoma cells [98] and also in breast cancer cells [115], we investigated if the decrease in antioxidant enzyme activities in invasive B16-F10 cells (iB16) knockdown for the GR (iB16-shGR) was associated with changes in nuclear Nrf1 and/or Nrf2. This evidence concerns the gene GSR and breast cancer.