cellproliferation

Cell proliferation is the process by which cells grow and divide to produce new cells, contributing to development, growth, tissue maintenance, and repair. It is tightly regulated to balance cell loss and replacement and to ensure genetic integrity. Proliferation proceeds through the cell cycle, comprising G1, S, G2, and M phases, with checkpoints that monitor DNA integrity and replication completion. Growth factors and mitogens—such as epidermal growth factor and platelet-derived growth factor—stimulate progression from G1 to S, while cyclin-dependent kinases and cyclins drive cell cycle transitions. Inhibitors such as p16INK4a and p21 can enforce arrest, often in response to DNA damage or contact inhibition, leading cells into G0, a quiescent state.

Stem and progenitor cells contribute to proliferation with self-renewal and lineage commitment, while differentiated somatic cells may have limited or no proliferative capacity. Tissue turnover varies: labile tissues (skin, intestinal epithelium) renew rapidly; stable tissues (liver, kidney) renew slowly and can be stimulated after injury; permanent tissues (neurons, myocardium) show minimal proliferative activity. Dysregulation of proliferation underlies many diseases. Hyperproliferation can drive hyperplasia and contribute to tumorigenesis when oncogenic mutations or loss of cell cycle control removes normal restraints. Conversely, insufficient proliferation impairs development, wound healing, and tissue regeneration.

Assessment of proliferation uses markers such as Ki-67, proliferating cell nuclear antigen (PCNA), and nucleotide analog incorporation (BrdU, EdU). Understanding cell proliferation informs fields from developmental biology to oncology and regenerative medicine.