IMMUNOHISTOCHEMICAL STAINING OF RAS ONCOGENE PRODUCT IN NEOPLASTIC AND NONNEOPLASTIC MESOTHELIAL TISSUES - IMMUNOREACTIVITY FOR N-RAS AND LACK OF IMMUNOHISTOCHEMICAL STAINING FOR HA-RAS AND K-RAS

Immunohistochemical staining of 36 malignant mesotheliomas and 45 case s of non-neoplastsic mesothelium including 20 specimens with signs of hyperplasia were investigated using murine monoclonal antibodies direc ted against p21 ras protein, Ha-ras protein, K-ras protein, and N-ras protein. All cases of non-neoplastic mesothelium and the majority of t he malignant mesotheliomas (78 per cent) showed cytoplasmic and often submembranous immunoreactivity in more than 50 per cent of the cells w ith both the pan-ras and N-ras antibody. No immunoreactivity was obser ved for Ha- and K-ras. There was no statistically significant differen ce with respect to immunoreactivity between neoplastic and non-neoplas tic mesothelium or between the various mesothelioma subtypes.