Laminin is a major glycoprotein specific to basement membranes. Hepatocellular carcinoma tissue synthesize and secrete abundant laminin. By DNA-protein interaction assays, we have identified nuclear factors specific to hepatocellular carcinoma cells. The comparison of nuclear factor binding by Southwestern analysis with B1 and B2 laminin promoters revealed different patterns of nuclear factor binding in different cells types. In hepatocellular carcinoma, HepG2 cells, a specific pair of proteins (P105 and P98) consisting of 105 and 98 kDa were identified as common nuclear factors for both B1 and B2 laminin promoters, while in completely diverse human glioma cells (U251), various different and greater number of nuclear proteins ranging from 212 to 68 kDa were detected to interact separately with laminin B1 and B2 genes.