NR4A1 and breast cancer: In addition, two CpG islands were identified in the promoter sequence of NR4A1 (Supplementary Fig. 1b), and the overall methylation frequency in the CpG islands of the NR4A1 promoter was significantly decreased by treatment with the DNA methylation inhibitor 5-azacytidine (Supplementary Fig. 1c), followed by increased NR4A1 mRNA levels in BC cells in a 5-azacytidine dose-dependent manner (Supplementary Fig. 1d).