Interestingly, after incubation with 300 μg/mL silica NPs for 6 h, the NOX2 expression in the TRPM2-LE cells was higher than that in the TRPM2-HE cells (Fig. 3(d)), but there was no change in the expression of NOX4 (Fig. 3(e)), suggesting that silica NPs induced ROS production in the TRPM2-LE cells by up-regulating the NOX2 activity. This evidence concerns the gene NOX4 and hereditary elliptocytosis.