The roles of FXYD3 (Mat-8) and FXYD5 (dysadherin) are unclear, but they appear to be overexpressed in some cancer cells (Arimochi et al., 2007; Nam et al., 2007), and FXYD6 and 7 are expressed in the brain (Geering, 2005). The gene discussed is FXYD3; the disease is cancer.