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. 2005 Sep 30;1(1):e4. doi: 10.1371/journal.ppat.0010004

Figure 1. PB1-F2 Protein Sensitizes Cells to Apoptosis in Response to Cytotoxic Stimuli.

Figure 1

(A) Expression of PB1-F2 protein enhanced cleavage of poly-A ribose polymerase (PARP) in response to cytotoxic agents. 293T cells were transfected with either PB1-F2 (F2) or influenza virus NP (NP) for 24 h and were subsequently treated for 6 h with 50 ng/ml TNFα, 5 ng/ml TNF-related apoptosis-inducing ligand, 100 μM cisplatin, or UV-irradiation at 60 J/m2 as indicated. All cells were collected 6 h later, lysed, and processed by immunoblotting for cleaved PARP.

(B) PB1-F2 protein predisposes cells to death by anoikis. A549 cells were transfected either with empty vector or with PB1-F2 and trypsinized 24 h post-transfection. Cells were incubated in PBS with 0.3% BSA for 15 min, pipetted onto microscope slides, and changes in cell morphology (membrane blebbing indicated by arrows) were visualized by phase-contrast microscopy [22].

(C) A subset of PB1-F2-expressing cells undergoes apoptosis. A549 cells were transfected with HA-tagged PB1-F2 for 24 h and stained for HA epitope and cleaved cytokeratin (M30).