FIGURE 5.

p38β MAPK regulates SOCE in HLMVECs. A, RT-PCR analysis of mRNA expression for p38 MAPK isoforms in HLMVECs and mLECs. Total RNA from HLMVECs and mLECs was isolated, and RT-PCR was performed to determine the expression of transcripts for p38 MAPK (α, β, γ, and δ) and GAPDH. B, HLMVECs were transfected with Sc-siRNA or siRNA specific to p38 MAPK isoforms (p38α, p38β, and p38γ). At 72 h after transfection, cells were used to determine expression of p38α, p38β, and p38γ by immunoblot. C–E, HLMVECs were transfected with Sc-siRNA or siRNA specific to p38α (C), β (D), or γ (E). At 72 h after transfection, cells were used to determine thrombin-induced Ca²⁺ entry as described above. Note the sustained Ca²⁺ entry in p38β-siRNA transfected cells (D), whereas in p38α-siRNA transfected cells the Ca²⁺ entry was blocked (C). Experiments were repeated at least three times, and the results shown are mean ± S.E. F, HLMVECs transfected with Sc-siRNA, p38α-siRNA, or p38β-siRNA were immunoblotted with anti-STIM1 mAb. Note that in p38α-siRNA-transfected cells STIM1 expression was reduced.