An in vitro study/analysis in human osteosarcoma U2-OS cells shows that NURR1 can transcriptionally repress β-catenin-mediated transactivation of Axin2, a degradation or negative β-catenin signaling regulator, and inversely β-catenin can repress the transcriptional activity of NURR1, suggesting a negative reciprocal regulatory loop is present between the two factors [60]. This evidence concerns the gene NR4A2 and osteosarcoma.