The cell cycle is a precisely controlled sequence of events in the life of a cell, responsible for cell growth, DNA replication, chromosome separation, and ultimately cell division, producing two genetically identical daughter cells. This process includes four main phases: G1 phase (gap phase 1), S phase (DNA synthesis phase), G2 phase (gap phase 2), and M phase (mitosis). At each stage of the cell cycle, a series of intricate signal transduction networks function by activating or inhibiting specific cell cycle regulatory proteins, such as cyclin-dependent kinases (CDKs) and their partner cyclins.