The inhibitory activity of the OGF-OGFr axis has also been assessed in vitro and in vivo against cancer cells derived from neuroblastoma, pancreatic adenocarcinoma, colon adenocarcinoma, head and neck squamous cell carcinoma, and renal, ovarian and breast tumors (Donahue et al. 2009; Hatzoglou et al. 2005; McLaughlin and Zagon 2012; McLaughlin et al. 1999a, b; Zagon et al. 1999a, 2009). This evidence concerns the gene PENK and cancer.