Then the same NSCLC samples pairs were studied for LOH of ARF/INK4a and p53. With ARF/INK4a primers, 23 of 70 cases (32.9%) were positive for LOH 5′ primers close to the ARF locus, 19 of 70 cases (27.1%) were positive for LOH 3′ primers close to the INK4a locus (average 30%), and 33 of 70 showed LOH for either one of these (47.1%). This evidence concerns the gene TP53 and non-small cell lung carcinoma.