An RNA polymerase I inhibitor; inhibits expression of the 47S rRNA transcript (IC50 = 60 nM), disrupts the structure of the nucleolus, and leads to removal of the RNA polymerase complex from rDNA by inducing dissociation and destruction of RPA194 through a proteasome-dependent mechanism; activates p53 in the nanomolar range; reduces viability of several cancer cell lines but not of non-cancerous cells (IC50s = 0.7, 1.9, ≥40, and 2.7 μM for A375, human diploid fibroblasts, primary human melanocytes, and HIMEC cells, respectively); inhibits tumor growth in melanoma and colon cancer mouse xenograft models when used at a dose of 25 mg/kg