How do growth factors contribute to the cell cycle?

Growth factors contribute to the cell cycle in several different ways. They bind to specific cell receptors, initiating a signaling cascade within the cell (this is known as receptor activation). Examples of these receptors are receptor tyrosine kinases (RTKs) or G-protein coupled receptors (GPCRs). Growth factors may also activate specific transcription factors which stimulate genes for cell growth, DNA replication, and division. Growth factor signaling also promotes expression, activation of cyclins and CDKs. Thus, they assist in driving cell cycle progression through different checkpoints such as G1/S and G2/M checkpoints. It is important to note each growth factor binds to a specific cell-surface receptor, making it a tightly regulated process.