RAC1 and nephrolithiasis: Our data show that xanthine stones can cause sloughing of principal cells and shorten the lifespan of Drosophila. Additionally, preventing RSC-mediated regeneration of the SCZ in the presence of allopurinol-induced kidney stones shortens the lifespan, although we cannot exclude effects on the midgut of expressing Rac1.N17 in esg+ ISCs/RSCs.