 Solution

Co-transfect a reference reporter gene expressed from a suitable constitutive promoter, such as a Renilla luciferase construct, alongside the experimental firefly luciferase reporter. Normalize experimental luminescence to the reference signal to reduce variation in transfection, cell number and recovery. The reference promoter must be insensitive to the tested Wnt signalling and HNF1β manipulations; otherwise the denominator introduces an apparent effect. Keep total transfected DNA comparable and confirm that the assay signals are within their measurable range.