Fig. 1.

Knockdown of STIM1 reduces Ca²⁺ influx and CRAC channel activity. (A) Western blot showing significant knockdown (KD) of STIM1 after transfection with an siRNA construct. (Upper) A typical gel. (Lower) Summary of aggregate data from three independent experiments. (B) Confocal microscopy images showing expression of STIM1 in mock-transfected cells and after knockdown of the protein. (C) Histogram depicts aggregate data from three independent experiments (each bar is the average from >30 cells). (D) Store-operated Ca²⁺ entry is significantly reduced after STIM1 knockdown. Cells were stimulated with thapsigargin in Ca²⁺-free solution for 10 min and then external Ca²⁺ was readmitted. Only the Ca²⁺ entry phase is shown. (E) Whole cell patch clamp recordings compare I_CRAC in a control cell and in one in which STIM1 has been knocked down. (F) Aggregate data from 9 control cells and 11 STIM1 KD cells are compared. Pipette contained InsP₃ and 10 mM EGTA. *P < 0.05.