O₂⁻ augmented the level of S70pBcl-2 by inhibiting the holoenzyme assembly of PP2A_B56δ. (A) Jurkat cells expressing hemagglutinin (HA)-tagged B56 family members (α, β, γ1, δ, and ε isoforms) were subjected to co-IP analysis using Bcl-2 as bait and IB for the indicated proteins. (B) Lysates from DDC-treated Jurkat cells were IP and IB with the indicated antibody (Ab). (C) Jurkat cells transfected with B56δ-specific siRNA (sequence A or B) were lysed and IB for the indicated proteins. (D-F) Lysates from DDC-treated or SOD1-silenced Jurkat cells were IP and IB using the indicated Abs. (G) Mitochondrial/cytosolic fractions from SOD1-silenced Jurkat cells were IB for the indicated proteins. The OMM protein VDAC1 served as a mitochondrial marker. (H) Confocal indirect immunofluorescence imaging of DDC-treated Jurkat cells. PP2A-C (left column) or B56δ (right column) is stained in green; Bcl-2 is stained in red. Colocalization of Bcl-2 and PP2A-C (left column) or B56δ (right column) appears yellow.