PSMA4 and breast cancer: Among the PSMA family genes, we observed that cg07435350, cg26165081, cg26868250 of PSMA1; cg10778455, cg106226670, cg15202134 of PSMA2; cg08095532, cg14211735 of PSMA4; cg08250978, cg13170147 of PSMA5; cg01757308 of PSMA6; cg17665883 of PSMA7; cg11858305, cg15865827, cg00262344, cg06377543, cg03162994, cg22027766, cg259833544, cg01070760, cg21248196 of PSMA8 indicated the highest level of DNA methylation in breast cancer (Figure S1).