ID1 and cancer: The proposed antitumor mechanisms, involved directly suppressing Aurora A and Aurora B kinase activity, inhibition of NF-κB activation (Toshie, 2008), triggering of apoptosis and autophagy (Mori et al., 2007), inducing accumulation of ROS in cancer cells but not in normal endothelial cells (Hattori et al., 2013), inhibition of the ERK1/2 and DNA binding-1 (Id-1) pathways, decreasing Bcl-2 expression (Tada et al., 2012), and suppressing hypoxia tolerance by up-regulation of E-cadherin in cancer cells with mutant KRAS (Nishi et al., 2020).