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. 2011 Jan 17;6(1):e16241. doi: 10.1371/journal.pone.0016241

Figure 1. TNFα cooperates with IFN-γ to sensitize human colon carcinoma cells to TRAIL-induced apoptosis.

Figure 1

A. TRAIL-induced apoptosis. TRAIL-resistant SW620 cells were either untreated (control), treated with IFN-γ (100 U/ml), TNFα (100 U/ml), or both IFN-γ and TNFα overnight, followed by incubation with recombinant TRAIL (100 ng/ml). Cell death was analyzed by PI staining and flow cytometry analysis. B. Percent TRAIL-induced cell death was calculated as % PI-positive cells in the presence of TRAIL (+TRAIL) - % PI positive in the absence of TRAIL (-TRAIL). Column: mean, bar: SD. C&D. Expression level of cell surface TRAIL receptors. SW620 cells were treated with IFN-γ, TNFα, or both IFN-γ and TNFα for approximately 24 h and stained with the receptor-specific antibodies, respectively. The stained cells were then analyzed with flow cytometry. Isotype-matched IgG control staining is depicted as gray areas, and DR4-, DR5-, T-R3- and T-R4-specific staining is depicted as solid lines. The mean fluorescent intensity (MFI) of DR4 and DR5 are quantified (D). Column: mean, bar: SD.