Nuclear expression of active phosphorylated SYK in high grade serous ovarian carcinoma tissue and its correlation with poor survival. (A) Immunohistochemical staining of phosphorylated SYK(Y525/526) and SYK on paraffin-embedded sections of a representative high-grade serous ovarian carcinoma (scale bar 50 μm). (B) pSYK(Y525/526) if localized to nuclear and cytoskeletal cellular fractions. Ovarian cancer cell lines were subjected to subcellular fractionation and prepared for Western blot analyses. pSYK and total SYK expression in the indicated fractions were examined. MEK1, EGFR, E2F1, histone H2B, and vimentin serve as positive controls for cytoplasmic, membrane, soluble nuclear, chromatin-bound, and cytoskeletal fraction enrichment, respectively. (C – F) The association between nuclear expression of pSYK, pEGFR and SYK and overall survival in primary high-grade serous ovarian carcinoma tumors were examined by Kaplan-Meier survival analysis and log-rank test (n = 42). (C) Correlation of high nuclear pSYK with patient overall survival. (D) Survival analysis of patients with high versus low nuclear pSYK levels in pre-chemotherapy serous ovarian carcinoma peritoneal effusion samples (n = 112). (E) Survival analysis of patients with high versus low pEGFR Y1197 levels in pre-chemotherapy serous ovarian carcinoma peritoneal effusion samples (n = 42). (F) Survival analysis of patients with high versus low total nuclear SYK levels in primary high-grade serous ovarian carcinoma (n = 42).