Abstract: The present invention relates to methods and compositions to activate or modify the expression or activity of selected genes or gene pathways in cells. The invention more particularly relates to methods of preparing cells that express selected genes or gene pathways by mutagenesis in vitro, ex vivo, or in vivo. The invention more preferably discloses methods of modifying a regulator gene or sequence in a cell, so that the activity or expression of a selected gene or gene product is modified, without the structure of said gene product being altered. This invention can be used to produce improved cells for use in various areas such as screening, production, genetic analysis, cloning, cell therapy products, etc.

Abstract: The invention relates to a process for the production of biologically active, dimeric TGF-.beta., to novel TGF-.beta.s and pharmaceutical compositions comprising it. TGF-.beta. produced by this process can be used in various therapeutic modalities.

Abstract: The process for the production of a dimeric, biologically active Transforming Growth Factor type .beta. (TGF-.beta.)-like protein or a salt thereof, comprising refolding the denatured monomeric form of the protein in the presence of a mild detergent that permits folding of the monomeric protein into a spatial conformation, which after dimerization, is the conformation associated with the biological activity, while retaining the monomeric protein in soluble form. Mild detergents include sulfobetaines, 3-(3-chlolamidopropyl)dimethylammonio-1-propanesulfonate, 3-(3-chlolamidopropyl)dimethylammonio-2-hydroxy-1-propane-sulfonate, digitonin, cholate and deoxycholate at a concentration of about 1 to 100 mM. Compositions containing a TGF-.beta.