The differential screening selected gene aberrative in neuroblastoma (DAN) subfamily, consisting of DAN, the Cerberus homologue Cer1, Coco, protein related to Dan and Cerberus (PRDC), Gremlin, uterine sensitization-associated gene 1 (USAG-1) and Sclerostin, possess a cystine-knot with eight cysteine residues making up the ring of the knot (Figure 2) [9]. This evidence concerns the gene GREM2 and neuroblastoma.