NOX1 and neoplasm: The extent of functional NOX1 expression in HT-29 and DLD-1 human colon cancer cells, as measured by the generation of ROS (Figures 2B and 2C; Supplementary Figure S1B and S1F) correlated well with the degree of tumor cell growth stimulation by IL-4 or IL-13; in the presence of near-complete NOX1 knockdown (which had no effect on the expression of the Type II IL-4R), IL-4 exposure did not affect the growth rate of the tumor cells (Figure 2D).