DKK4 and neuroblastoma: Only a few genes have been identified as AP-2ε target genes in mammals, including ITGA10 encoding integrin α10 (important for chondrocyte differentiation)49, COL2A1 (involved in modulation of cartilage development)50, DKK4 (associated with resistance to chemotherapy in colon cancer)51, and CDKNA1 encoding p21WAF1 (identified in neuroblastoma cells)52.