The Myocardin-related transcription factor A (MRTFA), alternatively known as Megakaryoblastic Leukemia 1 (MKL1), also plays a major role in the LBT of ERα positive BC cells, since its activation and nuclear accumulation mediate their endocrine resistance by initiating a partial transition from luminal to basal-like phenotype [11,12]. Here, ESR1 is linked to breast cancer.