Fig. 1. 2-APB- and CAI-evoked inhibition of CCE in HEK-293 cells. Increases in [Ca²⁺]_i are expressed as ratios of 340/380 nm fluorescence signals. Cells were incubated in the absence of Ca²⁺ but with thapsigargin (TG, 1 µM), which depletes intracellular Ca²⁺ stores and activates CCE. CCE was estimated as the difference between [Ca²⁺]_i increase in the presence and absence of TG (Basal). 2-APB and CAI were added 45 seconds and 300 seconds, respectively before 2 mM Ca²⁺. Individual traces show the responses to TG, CCE activation and the inhibitory effects of 2-APB (A) and CAI (C). Mean F340/F380 ratios from a series of experiments in the presence of increasing concentrations of 2-APB (B) and CAI (D). Values are the mean±s.e.m.