TNF and cancer: It was found that cancer cells treated with LPS (1 μg/mL) for 16 h displayed secretion levels of IL-8, IL-6, and TNF-α significantly higher than those of untreated cells, as illustrated in Figure 4A. Pretreatment of HT-29 cells with PD (5 μg/mL) for 24 h before LPS stimulation significantly reduced (225% vs. 167%) the increase in LPS-induced IL-8 production (Figure 4B).