NR4A1 and cancer: Breast cancer (BC) is the most frequently diagnosed cancer worldwide; with 2.3 million new cases in 2020, this accounts for 1 in 8 cancer diagnoses.[1] It is a highly heterogeneous disease that can be caused by a variety of distinct genetic alterations in mammary epithelial cells, requiring a combinatorial evaluation of the histopathology of the primary tumor and of the expression pattern of hormone receptors to determine the optimal patient treatment plan.