Growth differentiation factor 15, also known as PTGF-β, TGF-PL or MIC-1, has been hypothesised to serve as a secreted biomarker for activation of the p53 pathway in human cancer (Seetoo et al, 2003; Koopmann et al, 2004; Weber et al, 2005; de Wit et al, 2005; Brown et al, 2006), and in CRC MIC-1, serum levels and genotype were associated with decreased overall survival and extent of disease (Brown et al, 2003; Xue et al, 2010). This evidence concerns the gene TP53 and cancer.