Internal potassium determines MMP _s , and MMP_sis correlated with lifespan in WT strains. (A) Internal potassium as a function of external potassium. (B) MMP_s as a function of internal potassium. (C) Median replicative lifespan as a function of MMP_s. MMP_s was normalized to the WT strain grown in media with standard potassium and arginine as the nitrogen source. Shapes indicate the amount of external potassium. r indicates the Pearson correlation coefficient, and p is the P-value of the estimate. Internal potassium data are from same experiments used to generate Fig. 4 A. MMP_s data are from same experiments shown in Fig. 5 C. Median lifespan data are from same experiments shown in Fig. 5 B.