Rb/E2F regulates many genes that encode proteins required for the cell cycle. Using affymetrix microarrays we previously identified genes regulated by the Rb proteins p130 and p107, many of which are involved in the cell cycle. Several genes with unknown functions were also repressed by p130 and p107, of which some have recently been found to have various roles in mitosis, the spindle checkpoint and cytokinesis. This study focuses on the regulation of borealin/dasra/cdca8, which encodes a recently discovered member of the chromosomal passenger complex. It is recorded that borealin is a cell cycle regulator, down-regulated in response to p53/Rb-signaling, and up-regulated in many types of cancerous tissues.