Hynda K. Kleinman,** Mary L. McGarvey, Lance A. Liotta, Pamela Gehron Robey, Karl Tryggvason, and George R. Martin abstract: We have studied the extractability of type IV collagen, laminin, and heparan sulfate proteoglycan from EHS tumor tissue grown in normal and lathyritic animals. Laminin and heparan sulfate proteoglycan were readily extracted with chaotropic solvents from both normal and lathyritic tissue. The collagenous component was only solubilized fromlathyritic tissue in the presence of a reducing agent. These results indicate that lysine-derived cross-links and disulfide bonds stabilize the collagenous component in the matrix but not the laminin or the heparan sulfate proteoglycan. The majority of the collagen present in the extracts had a native triple helix based uponthe patternof peptides resistant to pepsin digestion