TRs are active in the absence of functional <i>BRCA1</i>.

<p>The TR target gene <i>CTNNB1</i> encoding β-Catenin was quantified in HCC3153 (<i>BRCA1</i>^mut) upon T3 stimulation. While T3 induced <i>CTNNB1</i> in HCC3153 expressing <i>THRA</i> as well as <i>THRB</i>, <i>CTNNB1</i> expression was significantly down-regulated upon T3 stimulation in HCC3153 silenced for <i>THRA</i> (A). Blocking TRs significantly reduced proliferation (B) and viability (C) of HCC3153 as quantified by BrdU (B) and WST-1 (C) assay, respectively. Reduced viability was also observed in HCC3153 silenced for <i>THRA</i> (D). Efficiency of <i>THRA</i> knockdown was validated on mRNA (E) and protein (F) level. <i>THRB</i> mRNA was not significantly altered in cells silenced for <i>THRA</i> (E). Mann-Whitney U Tests (B-D, F) and the REST2009 algorithm for determining relative gene expression (A, E) have been applied. Significant changes are indicated by stars (*) representative images are shown. scr—scrambled siRNA control, HiP—HighPerFect transfection reagent only control.