Fig. 9. Colchicine potentiates but does not activate SOCE in cells overexpressing STIM1. (A) HEK 293 cells expressing EYFP-STIM1 were treated with 1.0 µM CPA alone (Control; black trace) or with CPA and 100 µM colchicine (red trace) for 20 minutes in a nominally Ca²⁺-free extracellular solution, followed by addition of 1.8 mM extracellular Ca²⁺ to reveal SOCE. Also shown are data from cells treated with colchicine alone (blue trace). Each trace represents the average response of all cells on a single coverslip (20-30 cells). (B) The average difference between the peak 340/380 value following Ca²⁺ addition and the 340/380 value just before Ca²⁺ addition was calculated for CPA-treated control (n=64, three coverslips) and colchicine-treated (n=97, three coverslips) cells for experiments performed as described in (A). The data are reported as the mean±s.e.m.; the P value is based on t-test.