Defective SOCE in Stim1^−/− macrophages. (A) Mean blood monocyte counts (± standard deviation [SD]) in wild-type and Stim1^−/− chimeras (n = 5). (B) Mean PM numbers (± SD) isolated from wild-type and Stim1^−/− chimeras (n = 5, *P < .05). (C) Western blot analysis of STIM1 expression in wild-type and Stim1^−/− PM; β-tubulin served as a loading control. Top panel: densitometric analysis of 4 individual blots. The results shown are the mean signal intensities (± SD) for STIM1, each normalized to the signal intensity of the β-tubulin signal of the same sample (arbitrarily defined as 1.0). Bottom panel: representative blot. (D) Fura-2–loaded PM were stimulated with 5 μM TG for 10 minutes followed by addition of extracellular Ca²⁺ and monitoring of [Ca²⁺]_i. Representative measurements (left) and maximal (Δ[Ca ²⁺]_i ± SD) (n = 5 per group) before and after addition of 1 mM Ca²⁺ (right) are shown (***P < .001).