Dase for 30 min. The staining was then developed with 0.05 3',3-diaminobenzidine tetrahydrochloride prepared in 0.05 mol/L of Tris buffer at pH 7.6 containing 0.024 H2O2 and then counterstained with hematoxylin. Normal mesothelial tissue was used as a positive control. For a negative control, we used the same specimens used for the positive controls, replacing the primary antibody with PBS.Subce