ISG15 and cancer: The functions of most of the IRDS proteins have not been fully studied in cancer, but U-ISGF3-induced mRNAs and proteins, including IFI27 (ISG12), IFITM1 (LEU13), ISG15 (G1P2) and BST2, are upregulated in various types of cancers compared to normal tissues and in metastatic or recurrent cancers compared to the original lesions (Suomela et al, 2004; Andersen and Hassel, 2006; Hatano et al, 2008; Cai et al, 2009).