Substances causing differentiation

A method of determining the effects of a compound on a non-inducible promoter in a eukaryotic cell, comprising:

• a) incubating the eukaryotic cell in a culture medium containing an antibiotic corresponding to an antibiotic resistance gene, wherein said eukaryotic cell comprises a DNA construct, said DNA construct consisting essentially of a fusion gene under the control of the promoter, wherein the promoter is active in said culture medium without any specific requirements for promoter induction, wherein said fusion gene comprises the antibiotic resistance gene and a reporter gene, and wherein activity of the promoter is reduced in the absence of the antibiotic when expression of the resistance gene is not required for growth of the cell;
• b) inoculating a culture medium lacking said antibiotic with the incubated cells from step a);
• c) incubating the culture medium inoculated with the cells from step b) for about 5 hours to about 100 hours, wherein a basal activation level of the promoter in the absence of the antibiotic is achieved;
• d) checking the incubated cells from step c) for expression of the reporter gene to determine an amount of expression of the reporter gene in the absence of said compound;
• e) adding said compound to said culture medium of the cells from step c);
• f) incubating said culture medium with the cells and said compound for about 1 day to about 5 days;
• g) checking the incubated cells from step f) for expression of the reporter gene to determine an amount of expression of the reporter gene in the presence of said compound;
• h) comparing the amount of expression in the presence of said compound with the amount of expression in the absence of said compound from step d), wherein an increase in the amount of expression in the presence of said compound indicates that the compound has an effect on the promoter in said eukaryotic cell.