The expression of ras p21 and myc p64 was examined in imprint smears o
f 52 patients with lung cancer and 44 patients with benign disorders,
by immunochemistry. Imprint smears were-taken from fresh bronchial bio
psies during diagnostic bronchoscopy. Both ras and mye oncoproteins we
re found to give negative reaction in all benign examined cases; Of th
e 52 malignant bronchial tissue imprint smears, 28 (54%) and 30 (58%)
were positively stained with ms p21 and mye p64 antibodies respectivel
y. Positive staining of ras p21 was demonstrated in 54.5% of squamous
cell carcinoma, in 80% of adenocarcinoma and in 0% of small cell carci
noma 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 bot
h ras and myc oncoproteins detected in bronchial biopsies, may play a
crucial role in lung cancer.