GPER1 and neoplasm: In particular, GPER modulates signaling processes leading to the transcription of genes promoting tumor growth in vitro and in vivo, such as calcium mobilization, cAMP synthesis, the cleavage of matrix metalloproteinases, the transactivation of epidermal growth factor receptor (EGFR) and the activation of PI3K and MAPK transduction pathways (2–11).