(A) E2 elevated IGF-1R. MCF-7:5C cells were treated with vehicle (0.1% EtOH) or E2 (10−9 mol/L) for 72 hours. IGF-1R was examined by Western blotting. β-actin was measured as loading control. (B) Regulation of JNK activation by IGF-1R. MCF-7:5C cells were treated with vehicle (0.1% DMSO), E2 (10−9 mol/L), SP600125 (10−5 mol/L), E2 (10−9 mol/L) plus SP600125 (10−5 mol/L), AG1024 (5×10−6 mol/L), E2 (10−9 mol/L) plus AG1024 (5×10−6 mol/L) for 48 hours. p-JNK was examined by Western blotting. Total JNK was measured as loading control. (C) Regulation of JNK activation by PI3K. MCF-7:5C cells were treated with vehicle (0.1% DMSO), E2 (10−9 mol/L), LY294002 (10−6 mol/L), and E2 (10−9 mol/L) plus LY294002 (10−6 mol/L) for 48 hours. p-JNK was examined by Western blotting. Total JNK was measured as loading control. (D) Induction of apoptosis by the endoplasmic reticulum stress inducer, Tunicamycin. MCF-7:5C cells were treated with vehicle (0.1% DMSO) or Tunicamycin (10−5 mol/L) for 24 hours. Annexin V binding assay was used to detect apoptosis. p<0.001, ** compared with control. (E) Effects of Tunicamycin on the activation of JNK. MCF-7:5C cells were treated with the same compound as in (D). p-eIF2α and p-JNK were examined by Western blotting. Total eIF2α and JNK were measured as loading controls.