2.3 Western blotting
The proteins of the cultured cells and sperm samples were extracted using a universal protein extraction lysis buffer (Bioteke) containing a protease inhibitor cocktail (Roche). Then, denatured proteins were separated on 10% SDS-polyacrylamide gels and transferred onto a polyvinylidene difluoride (PVDF) membrane (Millipore) for immunoblot analysis. The primary antibodies used were anti-SLC26A8 (1:1000, Atlas antibody) and GAPDH (1:5000, Abcam).