FXYD4 and breast cancer: FXYD1 is also known as phospholemann (PLM), FXYD2 as γ, FXYD3 as Mat-8 (Mammary tumor marker), FXYD4 as CHIF (channel inducing factor), FXYD5 as dyshaderin or RIC (related to ion channel), and FXYD6 as phosphohippolin [115].