Calpastatin overexpression in tubular cells in vitro does not protect against aging. Prominin 1 positive proximal tubular cells have been isolated by flow cytometry and cultured during 5 months. After 12 passages, telomere lenght decreased similarly in cells from WT and CalpTG (TG) mice (A, n = 3). In addition, after 6 passages, a similar proportion of WT and CalpTG cells expressed p21, a classical marker of senescence (B, n = 3).