Fig. 6. Overexpression of STIM1 rescues inhibition by nocodazole. To evaluate SOCE, changes in the intracellular Ca²⁺ concentration were monitored in HEK 293 cells in which Ca²⁺ stores were depleted with thapsigargin (Tg; 2 µM) in the presence of a nominally Ca²⁺-free extracellular solution, followed by addition of 1.8 mM Ca²⁺. In wild-type HEK 293 cells overexpressing unconjugated EYFP (A) and cells overexpressing EYFP-STIM1 (B), SOCE was evaluated following a 20 minute incubation in 10 µM nocodazole (NZL; red traces) or 0.1% DMSO (black traces). Each trace represents the average response of all cells on a single coverslip (20-30 cells). (C) The average difference between the peak 340/380 value following Ca²⁺ addition and the 340/380 value just before Ca²⁺ addition was calculated for EYFP-expressing cells treated with DMSO (n=89, three coverslips) or 10 µM nocodazole (n=110, four coverslips) and in EYFP-STIM1-expressing cells treated with DMSO (n=77, three coverslips) or with 10 µM nocodazole (n=84, 3 coverslips) for experiments performed as described in (A) and (B). The data are reported as the mean±s.e.m.; the P values are based on t-tests.