Differential expression of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) family genes in CD11b+/Gr-1-/lo osteoclast precursors (OCPs) from tumor necrosis factor-transgenic (TNF-Tg) and wild-type (WT) mice. CD11b+/Gr-1-/lo cells from peripheral blood and bone marrow from TNF-Tg (7 mice per array) and WT (23 mice per array) mice were pooled and purified by flow sorting. The RNA samples were subjected to microarray analysis using the GeneChip mouse genome 430A 2.0 array from Affymetrix. The array data on angiogenic gene expression were analyzed using GeneTraffic software. The expression ratio was calculated by dividing the mean value of the intensity of RNA signals from two separate arrays of TNF-Tg OCPs by that from WT cells.