INDIGO's panel of TR reporter assays utilizes non-human mammalian cells engineered to express human thyroid hormone receptors alpha (NR1H3) and beta (NR1H2), ligand-dependent transcription factors commonly referred to as TR(alpha) and TR(beta). INDIGO's TR reporter cells include the luciferase reporter gene functionally linked to a responsive promoter. Thus, quantifying changes in luciferase expression in the treated reporter cells provides a sensitive surrogate measure of the changes in TR(alpha) or TR(beta) activity. The principal application of this assay panel is in the screening of test samples to quantify any functional activity, either agonist or antagonist, that they may exert against the human TR's. TR reporter cells are prepared using INDIGO