NOX4 and infection: In untranfected cells and in control siRNA treated cells, the PVs with 8 tachyzoites are approximately 40% of total PV population; however, in Nox4 siRNA-transfected cells, more than 50% of PVs contained 8 tachyzoites and even PVs with 16 tachyzoites (approx 10%) were observed after 24 h infection, demonstrating accelerated replication of T. gondii in these cells.