To characterize de-differentiated plant cultured cells and to determine factor(s) that regulate the de-differentiated state, comparative analyses of the gene expression profiles of intact plants and three different cultured cell lines of Arabidopsis were performed by DNA microarray and RNA blot analyses. The three different cultured cell lines (T87 and two cell lines newly induced from leaf and root tissue, respectively) were used. Twenty-seven to 140 genes were down-regulated but only 9-27 genes were up-regulated in each cultured cell lines when compared to the intact plants. Genes commonly regulated in each cultured cell lines were investigated and six genes, including those related to metabolism, were found to be down-regulated and two genes, that include those related to a transcription factor, were up-regulated.