FIG. 5.

H₂O₂ exposure stimulates RIP and TRAF2 interaction. (A) H₂O₂ treatment stimulated an early RIP and TRAF2 interaction in vivo After cells were exposed to H₂O₂ (500 μM), coimmunoprecipitation (IP) was performed using TRAF2 antibody and immunoblotted with RIP, TRADD, GRP78, and TRAF2. Results are representatives of five independent experiments. (B) Reverse coimmunoprecipitation in wt MEF cells. After cells were treated with H₂O₂ (500 μM) for 15 and 30 min, coimmunoprecipitation was performed using RIP antibody and immunoblotted with TRAF2 and RIP antibodies. Results are representative of three independent experiments. (C) Immunofluorescence staining of membrane lipid rafts and RIP. Cells were first labeled with FITC-CTxB, followed by H₂O₂ treatment (500 μM in DMEM, 37°C) for up to 30 min and finally RIP immunofluorescence staining. Cells were examined using a Zeiss confocal microscopy. Bar, 20 μm.