Figure 6. Luciferase assays with the SuperTopFlash cell line transfected with the indicated plasmids. SuperTopFlash (STF) cells/well were transfected with 800 ng DNA (200 ng of Norrin, 200 ng of FZD4, 200 ng of LRP5, 100 ng of pSV-β-galactosidase control vector, and 100 ng of TSPAN12 plasmid [wild-type or mutation]) and 1.5 µl Lipofectamine 2000 transfection reagent. Forty-eight hours after transfection, the cells were harvested and washed twice with PBS. Luciferase activities were measured with a dual-luciferase assay kit. Reporter activity was normalized to the coexpressed β-galactosidase activity in each well. Each test was performed in triplicate. The reporter assay was repeated three times, and a representative result was obtained.