In the clinic, tetrathiomolybdate (TTM) anions are used to chelate cupric cations and have been shown to potently inhibit SOD1, which uses cupric cations as a co-factor, leading to clinical trials of TTM as anti-cancer agents (Juarez et al., 2006; Lowndes et al., 2008; Redman et al., 2003). This evidence concerns the gene SOD1 and cancer.