NR4A1 and osteosarcoma: In “Osteoblastic”, differentially expressed NRs such as NR4A2, NR4A1, NR3C1, NR2F6, NR2F2, NR2F1, VDR, NR1H2, RORA, and THRA among metastasis, primary, and recurrent osteosarcoma tissues (Figure 4).