Figure 3.

Caspases are responsible for the cleavage of NMD factors UPF1 and UPF2 during apoptosis. (a) Measure of the apoptosis level in cells treated with DMSO, staurosporine (STS), STS and the caspase inhibitor zVAD-fmk (Z) or Z alone. (b) Western-blot analysis of PARP and caspase 3 shows the presence of cleavage product in the presence of STS, but not in the presence of STS with Z or Z alone. (c) Western-blot analysis of UPF1 or UPF2. Tubulin protein is used as control to ensure that the analysis of each lane can be comparable. * indicates nonspecific protein species. The three most-left lanes of each analysis represent a serial dilution from an untreated cell extract symbolized by a triangle. The protein molecular weight is indicated on the left side of each western-blot analysis. The protein cleavage products are indicated on the right side of the western-blot analysis. Error bar=S.D. Results showed in figure 3 are representative of at least three independent experiments