NR4A1 and breast cancer: For the discovery set, we collected samples from 329 women with primary breast cancer with poor prognosis features (defined by >2 cm cancers and/or lymph-node positive and/or hormone-receptor negative and/or grade 3) from 14 European centres at the time of diagnosis and before treatment commenced, and 869 women without breast cancer (593 from the general population and 276 from women attending hospital for benign women-specific conditions) (Fig. 1).