Hypermethylation of HIN-1 (Highly Inhibited in Neoplastic Cells 1), RAR-β (Retinoic Acid Receptor Beta), and RASSF1A (Ras Association Domain Family Member 1A) is significantly elevated in breast cancer metastases to the bone, brain, and lung, suggesting their potential as biomarkers for metastatic progression [28,30]. This evidence concerns the gene RARB and breast cancer.