Serum levels of fibronectin and a fibronectin-like DNA-binding protein in patients with various diseases.

The levels of fibronectin and the fibronectin-like, malignant disease-associated DNA-binding protein (MAD-2) were determined in sera from patients with various diseases. The levels of both proteins were elevated in most serum samples from patients with various types of cancer and in some patients with nonmalignant diseases. The highest levels of these proteins were found in patients with carcinomas of the breast and lung. A subset of the lung cancer patients with small cell carcinoma had either normal or depressed marker levels. The levels of fibronectin and MAD-2 varied concordantly in the different patient populations studied, which suggests that the serum levels of the fragment are directly proportional to the total amount of fibronectin in the serum.