Total RNA was extracted using 0.1 mL of RNA STAT-60 (ISO-TEX Diagnostics, Friendswood, Tex) according to the manufacturer's protocol, and RNA was resuspended in RNAse-free water. Biotinylated complementary DNA (cDNA) probes were then generated from RNA isolates using linear polymerase chain amplification. The Nonrad GEArray Ampolabeling kit (SuperArray Bioscience Corp, Bethesda, Md) was used to generate biotin-labeled probes. These probes were then hybridized to the GEArray Q Series Human Tumor Metastasis Gene Array kit (SuperArray) containing 96 specific cDNAs (300-600 base pairs) known to be involved in tumor growth and metastasis. The protease genes evaluated were matrix metalloproteinases MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-11, MMP-13, MMP-14, MMP-15, MMP-16, tissue inhibitor of metalloproteinases TIMP-1, TIMP-2, and TIMP-3, thrombospondin 1, plasminogen activator inhibitor 1 (PAI-1), elastase, cathepsin B, cathepsin L, cathepsin D heparanse, urokinase (uPA), and urokinase receptor (uPAR). Reference genes included blanks, glyceraldehyde phosphate dehydrogenase (GAPDH), and β-actin. The cDNA probes generated by linear amplification of the messenger RNA (mRNA) were denatured, and hybridization was conducted according to the manufacturer's protocol. Briefly, the nylon membranes were incubated overnight at 60°C with the biotin-labeled probe and washed twice in 1% sodium saline citrate (SSC) and twice in 1% sodium dodecyl sulfate (SDS) for 60 minutes each, then once in 0.1% SSC and twice in 0.5% SDS for 20 minutes each, all at 60°C. The membranes were exposed to film at room temperature with intensifying screens. The relative expression level of each gene was determined through densitometric scanning after digital capture with a Coolpix 4500 camera (Nikon USA, Melville, NY).