The importance of prolactin receptor antagonists is especially related to their potential to antagonize the tumor growth-promoting effects of hPRL in vivo, in animal models of breast and prostate cancer (Chen et al. 2002; Xu et al. 2001), and to their antiangiogenic properties (Ueda et al. 2006; 2009). The gene discussed is PRLR; the disease is prostate carcinoma.