Objectives To compare the gene expression profiles of acute promyelocytic leukemia cell line NB 4 before and after 12 hours of realgar treatment using cDNA microarray Methods Two cDNA probes were prepared through reverse transcription from mRNA of both untreated and realgar treated NB 4 cells The probes were labeled with Cy3 and Cy5 fluorescence dyes individually, hybridized with cDNA microarray representing 1003 different human genes, and scanned for fluorescent intensity The genes were screened through the analysis of the difference in two gene expression profiles Results The analysis of gene expression profiles indicates that 9 genes were up regulated and 37 genes were down regulated Among the 9 up regulated genes, 2 genes were involved in a proteasome degradation pathway Some genes related to protein synthesis, signal transduction and cell receptors were down regulated Conclusion PSMC2 and PSMD1 genes may play an important role in the apoptosis and partial differentiation of NB 4 cells Objectives To compare the gene expression profiles of acute promyocytic leukemia cell line NB 4 before and after 12 hours of realgar treatment using cDNA microarray Methods Two cDNA probes were prepared through reverse transcription from mRNA of both untreated and realgar treated NB 4 cells The probes were labeled with Cy3 and Cy5 fluorescence dyes individually, hybridized with cDNA microarray representing 1003 different human genes, and scanned for fluorescent intensity The genes were screened through the analysis of the difference in two gene expression profiles Results The analysis of gene expression profiles that that 9 genes were up regulated and 37 genes were down regulated Among the 9 regulated genes, 2 genes were involved in a proteasome degradation pathway Some genes related to protein synthesis, signal transduction and cell receptors were down regulated Conclusion PSMC2 and PSMD1 genes may play an important role in the apoptosis and partial di fferentiation of NB 4 cells