PRDM14 was identified by microarray analysis and was expressed in specifically undifferentiated human ES cells. PRDM14 protein is thought to regulate gene transcription in human ES cells, as it contains a PR domain, a subtype of the SET domain which catalyzes historic methylation. To analyze the function of PRDM14, we performed knock-down and forced expression of PRDM14 in human ES cells. Knock-down of PRDM14 by siRNA induced expression of early differentiation marker genes. Forced expression of PRDM14 suppressed expression of differentiation marker genes in the embryoid body. These results suggest that PRDM14 is involved in the maintenance of the self-renewal of human ES cells by suppression of gene expression. (c) 2008 Elsevier Inc. All rights reserved.