Immunocytochemical determination of p53, XPA and MSH2 expression in ovarian cancer cells. A. A2780/CP70 cells were treated for 1 h with 40 μM cisplatin. Cells were washed and incubated in drug-free media for 24 h and immunohistochemistry was performed. Representative pictures of cells at 20x magnification for secondary antibody only control (a), p53 (b), XPA (c) and MSH2 (d). B. Plot of 3,3'-diaminobenzidine (DAB)-positive cells. Data are single biological experiment performed in duplicate slides. Four different fields were counted per coverslip.