FIGURE 7.

SOK1 enters the nucleus in cells subject to chemical anoxia and is a substrate of caspases. A, a low molecular weight form of SOK1 enters the nucleus upon chemical anoxia. HEK293 cells were either left untreated or treated with sodium cyanide and 2-deoxyglucose for 3 h in the absence or presence of 50 μm z-VAD-fmk caspase inhibitor. Nuclei were separated from cytoplasm, extracts were prepared, and a Western blot against SOK1 was performed. The asterisk marks a band appearing in the nucleus of treated cells in a caspase-dependent manner. Western blots for the nuclear protein SP1 and the cytoplasmic protein GAPDH were performed to ensure proper separation of nucleus and cytoplasm (lower panels). B, SOK1 is a caspase 3 substrate. The caspase substrate Mst3 or SOK1 were in vitro translated in the presence of [³⁵S]methionine and incubated in the absence or presence of caspase 3 and the caspase inhibitor z-VAD-fmk. Reactions were separated by electrophoresis and exposed by autoradiography. FL, full-length.