[Oncogene products as tumor markers].

Monoclonal antibodies reactive with ras gene products were produced. Specificity of the antibodies obtained was determined by ELISA and immunoblotting assays. Using one of those anti-ras p21 monoclonal antibodies, RASK-3 the expression of p21 in human stomach cancer and thyroid cancer was studied by means of immuno-histochemistry. ras p21 was more dominantly expressed in cancer cells than in normal epithelial cells.