Figure 3.

PP2A interacts with full-length p70^s6k but not with a rapamycin-resistant p70^s6k mutant. (A) Western blot of PP2A in cell lysates and p70^s6k immune complexes. TAg Jurkat cells were treated with or without 25 nM rapamycin before lysis in buffer containing phosphatase inhibitors. They were then incubated with an α-p70^s6k polyclonal antibody or a control polyclonal antibody. The immunoprecipitated proteins were separated by using SDS/PAGE, and PP2A was visualized by Western blotting. (B) Western blot of HA-tagged p70^s6k in PP2A immune complexes. TAg Jurkat cells were mock-transfected or transfected with plasmids that express HA-tagged p70^s6k or a rapamycin-resistant, HA-tagged p70^s6k mutant that has been truncated at the N and C termini (NT/CT). PP2A was immunoprecipitated from the lysed cells, and proteins were separated by using SDS/PAGE. HA-tagged proteins were visualized by Western blotting.