Fig. 1.

Immunohistochemical expression of PARP1, γH2AX, BRCA1, and BRCA2 in human osteosarcomas. a Immunohistochemical expression of PARP1, γH2AX, BRCA1, and BRCA2 in osteosarcomas. PARP1 and γH2AX are expressed in the nuclei of tumor cells. BRCA1 and BRCA2 are expressed in both the cytoplasm and nuclei of tumor cells. b Statistical analysis for the determination of cut-off points for the immunostaining of PARP1, γH2AX, BRCA1, and BRCA2. The cut-off points for immunohistochemical staining were determined by receiver operator characteristic curve analysis at the highest area under the curve (AUC) value. The cut-off points for PARP1 (arrow), γH2AX (empty arrow), BRCA1 (arrow head), and BRCA2 (empty arrow head) expression were eight, eight, ten, and twelve, respectively