Figure 3. Effect of EcRE-2R-CAT on the growth and morphology of stably transfected C7-10 cells. Panel A shows untransfected control cells; Panel B shows cells transfected with EcRE-2L-CAT, in which the tandem pair of EcREs is in reverse orientation, relative to transcription of the CAT gene. Panel C shows C7-10 cells transfected with EcRE-2R-CAT. Cells were treated with 2 µg of DNA. The photographs show the appearance of cells 48 h after transfection, before addition of methotrexate (compare Table 1).