Kaplan–Meier survival curves for the overall survival (OS) and progression-free Survival (PFS) of MM patients according to CD138+ expression of miR-181a combined with R-ISS stage (a, b), high-risk cytogenetics (c, d) and response to 1st-line therapy (e, f). p-values calculated by log-rank test. sCR stringent complete response, CR complete response and VGPR very good partial response, PR partial response, SD stable disease, PD progressive disease.