While metadherin (named for metastasis adhesion protein) was first reported to be a transmembrane protein containing a “lung homing domain” that mediates lung metastasis of mouse mammary tumor cells,[23] it was later reported to reside in the cytosol, endoplasmic reticulum, nucleus and nucleolus, and its subcellular localization is closely linked to its various tumor‐promoting functions.[24, 42] How the context‐dependent localization of metadherin is regulated remains largely unresolved. The gene discussed is MTDH; the disease is breast cancer.