Previously, two studies suggested that ER-α expression can beregulated in BC cells by p5320 andTwist.21 However, p53 or Twist do notregulate ER-α in normal mammary epithelial cells while being constitutivelyexpressed in these cells22, 23 or overexpressed by inducers in BC cells (Banerjee,unpublished). This evidence concerns the gene TWIST1 and breast cancer.