In proliferating cells, the cell cycle consists of four phases. Gap 1 (G1) is the interval between mitosis and DNA replication that is characterized by cell growth. Replication of DNA occurs during the synthesis (S) phase, which is followed by a second gap phase (G2) during which growth and preparation for cell division occurs. Together, these three stages comprise the interphase phase of the cell cycle. Interphase is followed by the mitotic (M) phase. Mitosis and the production of two daughter cells occur in M phase. As the cell cycle controls cell replication and apoptosis, it is essential for the passage through the phases of the cell cycle and related processes to be regulated. Cyclin-dependent kinases (cdks), complexed with various cyclins, regulate the progression through G1-S-G2 phases by triggering DNA replication, transition from phase to phase, and transition into M phase. DNA synthesis occuring in the S phase is essential to passing on genetic information to daughter cells, but loss of genetic control of synthesis and the appearance of mutations can occur when regulatory feedback pathways are deregulated. In mitosis, aurora kinases control chromatid segregation, thereby making these serine/threonine kinases essential for cell proliferation. Apoptosis can be induced through several cellular mechanisms; these are discussed in more depth in the Discover Apoptosis technical article.
Dysregulation of the cell cycle has been shown to result in a number of diseases, most notably cancer and other proliferative diseases. Tools to study aspects of the cell cycle include mitotic inhibitors, CDK inhibitors, apoptosis inducers and inhibitors, DNA intercalators and crosslinkers, kinase inhibitors, and other bioactive small molecules for cell cycle regulation. We understand that when studying disease biology, it is essential to ensure that your target is the right target. We offer bioactive small molecules for target identification and validation in cell cycle research; a selection of these research tools is shown below.