A – GST-Binding assay for SERCA1 and Bcl-2Δ21. Rat skeletal muscle SR (2 µg protein) was incubated with 2 µg of GST-Bcl-2Δ21 in the absence or presence of different amounts of HSP70, followed by the pull-down with GST-agarose beads, SDS-page separation of bound proteins, and WB analysis with anti-SERCA1 and anti-HSP70 antibodies. B - Co-IP of Bcl-2Δ21 with HSP70 used as bait. HSP70 (2 µg) was incubated with different amounts of Bcl-2Δ21 (0–20 µg) in the absence or presence of SR (2 and 20 µg of total protein) prior to the pull-down with anti-HSP70 protein antibodies bound to protein G-agarose beads, followed by SDS-PAGE separation of proteins, and WB analysis with anti-Bcl-2 antibodies.