Total RNA was extracted by using the Qiagen RNeasy Mini Isolation Kit (Qiagen, Inc., Valencia, CA) and used according to the manufacturer's directions. Complementary DNA was synthesized by using the High Capacity cDNA Reverse Transcription Kit (Applied Biosystems, Carlsbad, CA) according to manufacturer's procedure. The level of mRNA for TGFβ1, CTGF, TGFβR2, SMA, collagen II, and 18S ribosomal RNA was determined by using the Real-Time PCR TaqMan Assay (Applied Biosystems, Carlsbad, CA). The primers and probes for each gene are described in Table A1. The endogenous control, 18S ribosomal RNA, was used to normalize target genes. Primers, probes, and cDNA were combined with TaqMan Universal PCR Master Mix (Applied Biosystems) and amplification was performed by the Applied Biosystems 7300HT Fast Real Time PCR System. The thermal cycling conditions were as follows: 2 minutes at 50°C, 10 minutes at 95°C, 40 cycles of 15 seconds at 95°C, and 1 minute at 60°C. The relative gene expression of the growth factors was calculated by using the 2-ΔΔCt method.