Gupta and colleagues37 reported that PXR activation promotes cell proliferation and tumor growth mainly through the upregulation of CYP3A4 and UGT1A1. However, these authors also suggest apoptotic gene downregulation as a potential mechanism of resistance in ovarian cancer, which is consistent with our observation of a nongenomic ligand-independent effect of PXR on p53-mediated function and apoptosis. This evidence concerns the gene UGT1A1 and neoplasm.