 Sixty-one patients with inflammatory bowel disease, 19 with Crohns colitis, 18 with Crohns ileitis and 24 with UC, undergo a colonoscopy with biopsies before and 4-6 weeks after the first infliximab treatment. Response to infliximab was defined based on endoscopic and histologic findings. A control group of 12 individuals was also included.Total RNA was isolated from biopsies, labelled and hybridized to Affymetrix HGU133plus2.0 Array. Microarray data were analyzed using Bioconductor software and Ingenuity Pathway Analysis software. Quantitative real time RT-PCR and immunohistochemistry were used to confirm microarray data. 