ABSTRACT
Transforming growth factor β (TGF-β) belongs to a family of sequence-related proteins involved in the regulation of growth and development across a wide phylogenetic span from Man to Drosophila. Based on partial amino acid sequence data, several oligonucleotides were chemically synthesized as hybridization probes, which enabled identification of a TGF-β exon in a human genomic DNA library. The ability of transformed cells to grow in semisolid medium as more or less spherical colonies was discovered in 1965 by MacPherson and Montagnier. Among the many characteristic biological changes shown by transformed cells, this capacity to grow in medium gelled with soft agar is one which is generally well correlated with in vivo tumorigenic potential of neoplastic cells. Platelet-derived growth factor alone does not induce normal rat kidney-49F cells to form colonies in serum-supplemented medium. Extracellular matrix components have important functions in tumorigenesis, embryogenesis, and tissue repair. Cells interact with matrix material at specific sites on the cell surface.
