Validation of Msx2 antibody specificity. (a) Western blot analysis of breast cell lines for Msx2 expression, showing Msx2 migrating at approximately 37 kDa. β-actin levels were used to evaluate protein loading. (b) Immunohistochemical staining for Msx2 on formalin-fixed, paraffin-embedded (FFPE) breast cell lines (×20 magnification). (c) Immunohistochemical staining for Msx2 on breast tumour tissue microarray (TMA) cores, showing examples of tumours with scores from 0 to 3 for nuclear and cytoplasmic staining (×20 magnification; scale bar represents 10 μm).