The present invention provides a novel polypeptide, Connective Tissue Growth Factor (CTGF), polynucleotides encoding CTGF, and including 5\u27 and 3\u27 untranslated nucleotides, antibodies reactive with CTGF and means for producing CTGF. Also provided are diagnostic and therapeutic methods for using CTGF, as well as an assay for identifying compositions which affect the expression of CTGF polynucleotide. The invention provides a novel TGF-.beta. responsive element upstream of the polynucleotide encoding CTGF structural gene