Alteration of cell division cycle regulation in human cancers: The role of CDKN2A gene

Cancer might be thought of as a disease characterized by a deregulated cellular growth. Thus, it is not surprising that some of the molecular components of cell division cycle machinery are altered in human tumors. The cell cycle of all post-embryonic eukaryotic cells (including malignant cells) is divided into four phases, namely: G1 phase (period prior to DNA synthesis), S phase (period of DNA synthesis), G2 phase (period between DNA synthesis and mitosis) and M phase (mitosis). Collectively, G1, S and G2 are called interphase, the cell cycle period distinct from division of the nucleus (mitosis) and cytoplasm (cytokinesis) (Pardee, 1989; Desai et al., 1992). The length of the S, G2 and M phases is remarkably similar in many different cells, while the greatest variation is seen in the length of G1. At some point late in G1, called restriction or R point, a cell becomes committed to traverse the remainder of the cell cycle. Thus, variations in cell cycle time are mostly due to variations in the length of G1 up to the R point (Pardee, 1989; Desai et al., 1992). These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.