['Proteinuria is associated with a progressive loss of renal function; we recently found that both intrarenal effects of proteinuria and the state of systemic nephrosis play an independent role in proteinuria-induced renal damage. Reduction of proteinuria is an important mechanism underlying the renoprotective effect of angiotensin-converting enzyme inhibition (ACEi). Both the reduction of proteinuria and the attenuation of the systemic state of nephrosis may be involved in the renoprotection by ACEi.', 'This article entails a post hoc analysis of a previous study on the renoprotective effect of ACEi lisinopril in adriamycin nephrosis. It was attempted to modify therapeutic efficacy of ACEi by increasing lisinopril dose and by dietary sodium restriction, respectively. In this analysis, we aimed to delineate the contribution of proteinuria reduction and the reduction of other intermediate parameters such as hyperlipidemia and blood pressure on the protection against focal glomerulosclerosis (FGS).', 'We found that in adriamycin nephrosis, ACEi significantly reduced proteinuria, lipids, and blood pressure and provided protection against FGS. Treatment modification by increasing the lisinopril dose resulted in a further reduction of FGS without significant effects on intermediate parameters (proteinuria, hyperlipidemia, and blood pressure), whereas surprisingly, treatment modification by sodium restriction resulted in a further attenuation of intermediate parameters, without additional protection against FGS.'] Is effect of proteinuria reduction on prevention of focal glomerulosclerosis by angiotensin-converting enzyme inhibition modifiable?