Detection of MAGE‐4 Protein in Sera of Lung Cancer Patients

We investigated the level of MAGE‐4 protein in sera of patients with primary lung cancer to understand better the biological roles of the MAGE proteins. MAGE‐4 protein was detected as a non‐degraded form in botb the supernatant of a MAGE‐4(+) tumor cell line and in a patient's serum. Serum level of the MAGE‐4 protein in lung cancer patients (n= 100, mean = 1.17 ng/ml) was significantly higher than that in either patients with benign pulmonary diseases (n= 80, 0.33 ng/ml) or healthy donors (n=68, 0.32 ng/ml). It was higher than the cutoff level (1.15 ng/ml) in 34 of 100 cancer patients, but not in anyone in the other groups.