Transcriptional regulation in response to hyperosmotic, high-salinity and oxidative stress, and abscisic acid (ABA) treatment in Arabidopsis suspension-cultured cell line T87 was investigated with a cDNA microarray containing 7000 independent full-length Arabidopsis cDNAs. The transcripts of 102, 11, 84 and 73 genes were increased more than 5-fold within 5h after treatment with 0.5M mannitol, 0.1M NaCl, 50 microM ABA and 10mM H2O2, respectively. On the other hand, the transcripts of 44, 57, 25 and 34 genes were down-regulated to less than one-third within 5h after treatment with 0.5M mannitol, 0.1M NaCl, 50 microM ABA and 10mM H2O2, respectively. Venn diagram analysis revealed 11 genes were induced significantly by mannitol, NaCl, and ABA, indicating crosstalk among these signaling pathways. Comparison of the genes induced by each stress revealed that 32%, 17% and 33% of mannitol-, NaCl- and ABA-inducible genes were also induced by H2O2, indicating the crosstalk between the signaling pathways for osmotic stress and oxidative stress. Although the expression profiles revealed that the T87 cells had most of the regulatory systems seen in Arabidopsis seedlings, the T87 cells did not have one of ABA-dependent signaling pathways.