A novel gene, CRG-L2, also known as CLOM; COLM collomin; FLJ23917; colmedin, gliomedin, (Cancer related gene-Liver 2), displays high expression in murine and human hepatocellular carcinomas (HCC). Its restricted expression in normal tissues and unique early upregulation during tumor development make CRG-L2 an excellent candidate as a new clinical marker of HCC. CRG-L2 is a member of the collagen superfamily. Collagens are generally extracellular structural proteins involved in formation of connective tissue structure. The sequence is predominantly repeats of the G-X-Y and the polypeptide chains form a triple helix. The first position of the repeat is glycine, the second and third positions can be any residue but are frequently proline and hydroxyproline. Collagens are post-translationally modified by proline hydroxylase to form the hydroxyproline residues. Defective hydroxylation is the cause of scurvy. Some members of the collagen superfamily are not involved in connective tissue structure but share the same triple helical structure.