Several studies also evidenced that p21 gene expression is negatively regulated by the β-catenin/TCF signaling and consequently that β-catenin inhibition leads to p21 accumulation in different cell lines including Human Embryonic Kidney (HEK) 293 cells, vascular smooth muscle cells and breast cancer cells [31,32,33]. The gene discussed is HNF4A; the disease is breast carcinoma.