GPER1 and breast cancer: The GPER-1 mediated signal pathways in cancer cells, and normal cells other than osteogenic cells, that have been reported, such as GPER-1 activation, stimulate cyclic AMP (cAMP) production, [9,18] calcium mobilization [19,20], c-Src expression and matrix metalloproteinase (MMPs) activation in breast cancer cells and other tissues [21,22].