PP2A interacts with CTLA-4 through the lysine rich domain and tyrosine 182. A) Association of CTLA-4 with the A subunit of PP2A. Jurkat T cell lines stably transfected with CTLA-4 variants were cultured overnight in the presence of doxycycline (1 μg/ml) to induce the expression of CTLA-4. Cell lysates were prepared and used for immunoprecipitation of PP2AA, followed by immunoblotting for CTLA-4, PP2AA and PP2AC. B) Association of CTLA-4 with the C subunit of PP2A. Jurkat cells were cultured and lysed as in A) and used for immunoprecipitation of PP2AC, followed by blotting for CTLA-4, PP2AA and PP2AC. Beads, immunoprecipitating Ab without cell lysate. Blots are representative of at least 3 independent experiments.