SMAD2 and cancer: Furthermore, the suppression of other CDKIs by SMAD2/3-NANOG-OCT4-EZH2-SNON in hPSCs could also support the proliferation capacity of cancer stem cells, considering the tumor-promoting effects of SNON (Edmiston et al., 2005; He et al., 2003; Krakowski et al., 2005; Zhu et al., 2005).