NOX1 and neoplasm: Concordant with the effect of IL-4 on NOX1 expression and ROS production in these cell lines, IL-4 exposure significantly increased tumor cell proliferation in both parental HT-29 and scrambled shRNA control cells over a 96 h period of observation (P < 0.001), and modestly increased proliferation in Si6/G6 cells (Figure 2D).