The purpose of this study is to determine whether the improved responsiveness to treatment achieved by CsA in patients with steroid-resistant or steroid-dependent FSGS could be explained by CsA's inhibitory action on the circulating suPAR expression.

Inclusion Criteria:

• Age at entry is between 14 and 70 years
• biopsy-proven primary FSGS
• proteinuria >=3 g/day
• without corticosteroids or CsA treatment before entry

Exclusion Criteria:

• Chronic Inflammatory Diseases
• malignant tumor
• diabetes mellitus
• contraindications for the treatment of corticosteroids or CsA treatment
• untolerate to or unwilling to accept corticosteroids or CsA treatment

1)the patients with steroid-sensitive FSGS;2)the cyclosporine A-treated patients with steroid-dependent and steroid-resistant FSGS;3)the healthy volunteers