CCND1 and cancer: Although the exact mechanism of the anti-cancer effect of KLF6 remains elusive, some classic pathways have been described: activating p21 through p53-independent mode (Narla et al., 2001), reducing the cyclin D1/CDK4 complex through interaction with cyclin D1 (Benzeno et al., 2004), inhibiting c-Jun proto-oncoprotein activities (Slavin et al., 2004), decreasing vascular endothelial growth factor (VEGF) expression (DiFeo et al., 2006b), up-regulating E-cadherin (DiFeo et al., 2006a), and inducing apoptosis (Ito et al., 2004; Figure 1).