Fig. 1: Bcl-xL overexpression inhibits IP₃R-mediated Ca²⁺ release in living cells.

Ca²⁺ signals were measured in Fura-2-loaded HEK cells expressing empty vector (pCMV24-P2A-mCherry; black), Bcl-2 (pCMV24-3xFLAG-Bcl-2-P2A-mCherry; orange) or Bcl-xL (pCMV24-3xFLAG-Bcl-xL-P2A-mCherry; green). EGTA (3 mM) was added to chelate extracellular Ca²⁺. IP₃R-mediated Ca²⁺ release was evoked by ATP (10 µM) (a–e) or carbachol (Cch, 10 µM) (f–j). Ionomycin (iono, 5 µM diluted in 250 mM CaCl₂) was added to assess the maximal Ca²⁺ response. Representative single-cell Ca²⁺ responses obtained from one well containing about 20–40 cells are shown (a–c, f–h). For each condition, six to nine different wells obtained from two to three independent transfections were monitored. Percentages of responding cells (d, i) and areas under the curve (e, j) were calculated from the Ca²⁺ traces. Data are represented as mean of wells ± SD (N = 6–9), each data point represents one well. Statistically significant differences were determined using a one-way ANOVA (*P < 0.05).