DKK1 and synovial sarcoma: Wnt signaling is also implicated in the pathogenesis of synovial sarcoma; synovial sarcoma cells frequently show accumulation of β-catenin protein in the nucleus [13], and express Wnt target gene products such as AXIN2 (axis inhibition protein 2), DKK1 (dickkopf1), survivin, c-MYC, and cyclinD1 [14].