Origin of laminin in the extracellular matrix of human tumor xenografts in nude mice.

Monoclonal antibodies reacting exclusively with laminin of human origin and a polyclonal antibody reacting with both murine and human laminin were used to immunohistochemically study the extracellular matrix of four human tumors grown as xenografts in nude mice: a lung carcinoma and a yolk sac carcinoma because they produced cell associated laminin in vitro; and two hepatocellular carcinomas which did not produce cell associated laminin in vitro. The extracellular matrix of the xenografts of the lung carcinoma and the yolk sac carcinoma contained laminin of both human and murine origin. Xenografts of liver carcinoma contained only laminin of mouse origin. This shows that the malignant cells capable of laminin production in vitro contribute this glycoprotein to the extracellular matrix of the solid tumor formed by them in vivo.