GPER1 and neoplasm: While leptin receptor expression in monocytes is highest among leucocyte subtypes, and leptin induces monocyte proliferation and IL-6 inflammatory responses [60], thus favouring a pro-tumorigenic phenotype, oestrogens acting via ERα and GPER inhibit IL-6 inflammatory responses and induce an anti-inflammatory profile [61], thus facilitating the tumour suppressing properties of monocytes.