HGF and cancer: Consistent with this hypothesis, paracrine growth factors that are normally secreted by prostate stroma cells, such as epidermal growth factor (EGF), insulin-like growth factor 1 (IGF1), hepatocyte growth factor (HGF), keratinocyte growth factor (KGF) or interleukin 6 (IL6), are found to be overexpression in hormone-refractory cancer in association with a switch to autocrine production by cancer epithelial cells [16].