This MAb specifically precipitates heterogeneous material of high MW, identified as perlecan, a major heparan-sulfate proteoglycan (HSPG) within all basement membranes and cell surfaces. It does not cross-react with laminin, fibronectin, or dermatran sulfate proteoglycan. Because of perlecan's strategic location and ability to store and protect growth factors, it has been strongly implicated in the control of tumor cell growth and metastatic behavior. Perlecan possesses angiogenic and growth-promoting attributes primarily by acting as a co-receptor for basic fibroblast growth factor (FGF-2). Suppression of perlecan causes substantial inhibition of neoplastic growth and neovascularization. Thus, perlecan is a potent inducer of neoplasm growth and angiogenesis in vivo and therapeutic interventions targeting this key modulator of tumor progression may improve neoplastic treatment.