RPS6KA5 and breast cancer: Low MSK1 expression was also significantly associated with the development of distant metastasis (χ2 = 13.850, df = 1, P < 0.001), recurrence (including local/regional recurrence and distant metastasis) (χ2 = 6.220, df = 1, P = 0.013) and breast cancer-related death (χ2 = 6.711, df = 1, P = 0.01).