MED1 and breast cancer: MED1 and MED24 have also been found to interact to mediate oestrogen receptor (ER) functions and regulate pubertal mammary gland and BC development.14 Because of the association of other Mediator proteins with ER, the role of MED7 in ER+ BCs was also explored, as ER+ BCs remain the most heterogeneous molecular group.15, 16 Overall, this study aimed to investigate the clinicopathological and biological significance of MED7 in BC including its role in LVI and hormonal receptor status.