Proteinuria is a major prognosis factor of chronic kidney disease (CKD) progression. Convergent evidences from clinical and experimental studies indicate that albuminuria and proteinuria are not simply a marker of CKD progression, but an active player in the evolution of the disease. Mechanistically, it has been shown that proteinuria induces endoplasmic reticulum stress in tubular cells, leading to induction of lipocalin 2/NGAL, a critical element of CKD progression. Moreover, proteinuric mice treated with phenylbutyrate are protected from CKD progression.