To test this hypothesis an alternative model was used, where nos2 expression was first induced in HCT-8 cells by addition of cytokines (TNF-α (200 ng/mL), IL-1α (200 ng/mL, IFN-γ (500 ng/mL) prior to Giardia infection (40 h later). The gene discussed is NOS2; the disease is giardiasis.