DKK4 and gastrointestinal stromal tumor: Dickkopf 4 (DKK4), as we have demonstrated before as a negative regulator of the Wnt pathway in GIST [19], was also lower in ETV4-high (metastatic, imatinib-resistant tumors with a mitotic rate >10/50 HPF) compared to ETV4-low (primary, untreated tumors with a mitotic rate ≤5/50 HPF) human GISTs (Figure 6C, right).