What part of the cell cycle would you expect that a change in regulation could result cancer?

The G1/S Transition of the Cell Cycle

The cell cycle is the process by which a cell grows and divides. It is divided into four phases: G1, S, G2, and M. The G1 phase is the first phase of the cell cycle, and it is during this phase that the cell grows and prepares for DNA replication. The S phase is the second phase of the cell cycle, and it is during this phase that the cell's DNA is replicated. The G2 phase is the third phase of the cell cycle, and it is during this phase that the cell checks for DNA damage and prepares for mitosis. The M phase is the fourth and final phase of the cell cycle, and it is during this phase that the cell divides.

A change in regulation in the G1/S transition could lead to the formation of cancer due to this transition being the main pathway through which cells either enter the cell cycle or arrest growth. For instance, if a cell fails to arrest growth when DNA damage is detected, the cell may proceed into the S phase with damaged DNA. Mutations in genes that regulate this checkpoint may lead to genomic instability and tumorigenesis.