Here we unveil that 1,25(OH)2D3-bound VDR activates Silent Information Regulator of Transcription, sirtuin 1 (SIRT1), leading to β-catenin deacetylation and nuclear exclusion, downregulation of its pro-tumourigenic target genes and inhibition of human colon carcinoma cell proliferation. The gene discussed is VDR; the disease is colon carcinoma.