FIGURE 1.

RSK2 binds to caspase-8 ex vivo. A, RSK2 interacts with endogenous caspase-8. A HeLa cell extract was used for immunoprecipitation (IP) with a caspase-8 antibody or control IgG overnight at 4 °C. Immunoprecipitated RSK2 was visualized by Western blot with an RSK2 antibody. B, structure and schematic diagrams of caspase-8 deletion mutant constructs. C, identification of the caspase-8 protein domain that interacts with RSK2. Various individual caspase-8-C360A-HA deletion mutants and RSK2 were co-transfected into HEK293 cells and cultured for 36 h. Extracted proteins (400 μg) were immunoprecipitated with anti-Xpress overnight at 4 °C. The immunoprecipitated caspase-8 was visualized with anti-HA by Western blotting, and the protein abundance of caspase-8 was also analyzed in cell lysates (20 μg) by Western blotting using anti-HA. IB, immunoblot.