ESR1 and breast cancer: The goals of this study were to determine whether ERα transrepresses the expression of interleukin 6 (IL-6), a cytokine that is linked to breast cancer cell invasion and motility as well as resistance to chemotherapy (Tamm et al, 1991; Conze et al, 2001), and to identify signalling pathways that may modulate transrepression by altering the stability of ERα.