The progression in renal fibrosis and the reduction in renal NCC and Slc3a1 levels with advanced age in Six2Cre+Tfap2bfl/WT mice was associated with an increase in β-catenin/mTOR hyperactivation (increased active β-catenin and increased phosphorylation of GSK-3β, p70 S6 kinase, 4E-BP1, and TFEB), similarly as observed in 1-2 months old Six2Cre+Tfap2bfl/fl mice (Fig. 4d; Supplementary Figs. S14a–d). Here, SLC3A1 is linked to renal fibrosis.