Figure 6. Zhangfei co-immunoprecipitates with Xbp1s in MG132-treated cells.

A. Vero cells were transfected to express Xbp1s and FLAG-tagged Zhangfei either on their own alone or together. The cells were treated with MG132 to reduce proteasomal degradation and, 24 hr later, cells lysates were immunoprecipitated with mouse anti-FLAG antibody. The precipitates were separated by SDS-PAGE and Xbp1 and Zhangfei detected in immunoblots with rabbit anti-Xbp1 or anti-Zhangfei antisera. Lanes 1-3, represent cell lysates without immunoprecipitation while lanes 4-6 are immunoblots of material precipitated by anti-FLAG antibodies. B. A similar experiment as in A, showing that Xbp1s was not co-precipitated with the Zhangfei mutant ZF(L/A).