The expression of ras p21 and myc p64 was examined in imprint smears of 52 patients with lung cancer and 44 patients with benign disorders, by immunochemistry. Imprint smears were-taken from fresh bronchial biopsies during diagnostic bronchoscopy. Both ras and mye oncoproteins were found to give negative reaction in all benign examined cases; Of the 52 malignant bronchial tissue imprint smears, 28 (54%) and 30 (58%) were positively stained with ms p21 and mye p64 antibodies respectively. Positive staining of ras p21 was demonstrated in 54.5% of squamous cell carcinoma, in 80% of adenocarcinoma and in 0% of small cell carcinoma imprint smears. Positive staining of myc p64 was demonstrated in 45.4% of squamous cell carcinoma, in 50% of adeno-carcinoma and in 100% of small cell carcinoma. The results of this study indicate that both ras and myc oncoproteins detected in bronchial biopsies, may play a crucial role in lung cancer.

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