Our results indicate that MSK1 prevents metastatic progression of ER<sup>+</sup> breast cancer, suggesting that stratifying patients with breast cancer as high or low risk for early relapse based on MSK1 expression could improve prognosis.
This association between high MSK1 expression and improved breast cancer-specific survival was observed in the whole cohort (P = 0.009) and in the HER2-negative and non-basal like tumours (P = 0.006 and P = 0.024, respectively).
Using the breast cancer cell line T47D, we show that estrogens (E2) and progestins activate MSK1, which forms a complex with the corresponding hormone receptor.