cDNA microarray analysis of changes in gene expression in primary HUVEC cultured in the absence or presence of homocysteine. [³²P]-labeled cDNA probes generated from poly (A)⁺ RNA from control HUVEC (A) or HUVEC exposed to 5 mmol/L homocysteine for either 4 (B) or 18 hours (C) were hybridized to a cDNA microarray containing 588 known human genes. After a series of high-stringency washes, hybridization patterns were analyzed by autoradiography. Upward or downward arrows indicate the location within the array of genes increased or decreased, respectively, by homocysteine at 4 or 18 hours, v untreated cells. The relative expression levels of specific cDNAs was assessed by comparison with a wide range of housekeeping genes. Results are representative of 2 separate hybridization experiments.