Fig. 5. RyR3-expressing cells display spontaneous localized Ca²⁺ signals. (B) Typical spontaneous Ca²⁺ signals recorded using confocal microscopy of single Fluo-3-loaded RyR3-expressing cells. The subcellular regions from which the localized Ca²⁺ signals were recorded are depicted by white circles. The dashed lines indicate the borders of the cells. A and C illustrate the lack of spontaneous Ca²⁺ signals in RyR1-expressing cells and control cells, respectively.