Figure 5 .

STIM2 regulates calcium-induced AMPK activation. A, B) Cytosolic calcium influx promotes STIM2–AMPK interaction. HEK 293T (A) and HeLa (B) cells stably expressing STIM2-SFB were incubated with medium containing ionomycin (1 μM) or thapsigargin (1 μM) for 30 min. Cell lysates were subjected to immunoprecipitation using S-protein beads. Coprecipitates were analyzed by Western blotting. C–F) STIM2 modulates calcium-induced AMPK activation. STIM2-deficient 786-O (C, D) or HeLa (E, F) cells were incubated with medium containing ionomycin (1 μM) or thapsigargin (1 μM) for the indicated time points for 786-O cells or for 30 min for HeLa cells. Cell lysates were then analyzed by immunoblotting for the phosphorylated and total levels of indicated proteins. G, H) Thapsigargin-induced Ca²⁺ influx in control and STIM2-depleted 786-O (G) or HeLa cells (H) was measured with Fura-2 AM. Error bars denote sem [n = 20 (control), n = 20 (STIM2 sg1), n = 20 (STIM2 sg2) (G); n = 50 (control), n = 83 (STIM2 sg1), n = 67 (STIM2 sg2)] (H).