NOX4 and cancer: TGF-β1 treatment resulted in upregulation of NOX2/4 and rapid intracellular production of ROS, which coincides with procurance of cancer associated cellular characteristics such as enhanced cell migration, proliferation, invasion, etc. Downregulating NOX through siRNA treatment demonstrated that early induced NOX2 promoted cell motility, while the delayed NOX4 induction drives cell proliferation upon cytokine induction.