Besides a positive correlation of TKTL1-expression, aerobic glycolysis, and the aggressiveness of different cancer types, targeted knockdown of TKTL1 in vitro already demonstrated its functional relevance for both growth and metabolism of cancer cells (Coy et al. 2005; Langbein et al. 2006; Krockenberger et al. 2007; Zhang et al. 2007; Hu et al. 2007). Here, TKTL1 is linked to cancer.