Aggressive expression of KITLG mediated by the autocrine/paracrine stimulation-loop mechanism has been identified in multiple cancer types such as uveal melanoma (Lefevre et al., 2004), glioma (Sun et al., 2006), breast cancer (Han et al., 2008), and non-small-cell lung cancer (Théou-Anton et al., 2006; Martinho et al., 2008; Levina et al., 2010). The gene discussed is KITLG; the disease is breast cancer.