The association among failure to downregulate pluripotency genes, the elevation of Nodal/Smad2 signaling, and failure to undergo cell cycle arrest has been reported by multiple investigators studying Dnd mutants (Cook et al., 2011; Heaney et al., 2012; Yamaji et al., 2017; Ruthig et al., 2019; Ruthig et al., 2021), and other models of germ cell tumor development (Spiller et al., 2012; Schemmer et al., 2013). Here, SMAD2 is linked to testicular germ cell tumor.