[Cell cycle and apoptosis]

The progression of cell cycle in embryonic cells from oceanic bionts to mammalians is initiated, promoted and terminated under the regulation of cell cycle gene products, named cyclins, and a p34 (cdc 2). Besides, oncogene (proto-oncogene) products such as p53 and pRB also directly regulate the progression of cell cycle. However, the p34 (cdc 2) which promotes the mitotic cell division also initiates the apoptosis of certain cells. Therefore, mutations of genes that regulate the normal progression of cell cycle would cause cells in the cell cycle undergoing either apoptosis or uncontrollable proliferation.