H19 and breast carcinoma: Several mechanisms can induce H19 expression in breast cancer cells, including: (i) activation from within the cell by upregulation of E2F1 (Berteaux et al., 2005), c-MYC (Barsyte-Lovejoy et al., 2006), or the loss of the tumor suppressor p53 (Dugimont et al., 1998); or (ii) activation by external stimuli, such as TGF-β, hypoxia, and HGF/SF.