The total RNA was extracted from kidney tissues using Trizol reagent (Invitrogen, Carlsbad, CA, USA). The mRNA levels of podocin and nephrin were determined by quantitative RT-PCR. The primers used were as follows: podocin, 5′-CTTGGCACATCGATCCCTCA-3′ and 5′-CTCTCCACTTTGATGCCCCA-3′; nephrin, 5′-AACCGAGCCAAGTTCTCCTG-3′ and 5′-GGACGACAAGACGAACCAGT-3′; GAPDH, 5′-GGAGTCTACTGGCGTCTTCAC-3′ and 5′-ATGAGCCCTTCCACGATGC-3′.