PLXNB1 and borderline ovarian serous tumor: To elucidate the expression of Plexin-B1 protein during serous ovarian carcinogenesis and to study the association of Plexin-B1 expression with clinical-pathological parameters, the expression levels of this protein in normal human ovaries, benign ovarian tissue, serous borderline ovarian tumors and malignant ovarian tumors were investigated with immunohistochemistry.