GJB2 and breast cancer: While the role of Cx26 hemichannels in the context of the mammary gland is unclear, genetically-modified mice with mammary gland specific expression of the G45E or S17F Cx26 mutants, which differ in their respective gap junction channel and hemichannel function, may provide more clarity on the role of Cx26 hemichannels in breast cancer [40, 41].