Methods of identifying inducible inhibitors of transformation progression

A method of isolating a gene which inhibits the expression of a gene regulated by a long terminal repeat of a Moloney leukemia virus comprising:

• a) introducing DNA containing the long terminal repeat regulated protein kinase C B.sub.1 gene of pMV7-PKC into a population of Ad5-transformed cells, E11 cells;
• b) treating the cells resulting from step (a) with a DNA demethylating agent so as to induce the expression of at least one progression suppressor gene and thereby suppress expression of the long terminal repeat regulated protein kinase C B.sub.1 gene;
• and
• c) isolating the gene which inhibits the function of the long terminal repeat.

A method of isolating a gene which activates the expression of a gene regulated by a long terminal repeat of a Moloney leukemia virus comprising:

• a) introducing DNA containing the long terminal repeat regulated protein kinase C B.sub.1 gene of pMV7-PKC into a population of Ad5-transformed cells, E11 cells;
• b) treating the cells resulting from step (a) with a DNA demethylating agent so as to induce the expression of at least one progression suppressor gene and thereby suppress expression of the long terminal report regulated protein kinase C B.sub.1 gene;
• c) treating the cells resulting from step b) with an amount of protein kinase C activating compound or an inhibitor of serine or threonine specific protein phosphatase effective to activate the expression of the gene regulated by the long terminal repeat;
• and
• d) isolating the gene which activates the expression of the gene regulated by the long terminal repeat.