Leptin-leptin receptor (OB-R) and IL-1 are pro-inflammatory cytokine systems promoting angiogenesis linked to worse prognosis of breast cancer.We have previously reported that leptin up-regulates VEGF/VEGFR-2 and IL-1 in breast and endometrial and cancer, respectively.However,whether leptin effects on VEGF are related to IL-1 in breast cancer is unknown.Several genetic and kinase pharmacologic approaches were used to dissect the mechanisms of leptin regulation of IL-1 system (IL-1α,IL-1β, IL-1Ra, IL-1R tI) in 4T1 cells.Basal levels of IL-1α were 14 fold higher than IL-1β in 4T1 cells.