Cell proliferation refers to the process by which cells divide and reproduce, resulting in an increase in the number of cells. This is a fundamental process for growth, tissue repair, and regeneration in multicellular organisms. Proliferation involves a series of tightly regulated steps in the cell cycle, where cells go through different phases: G1 (cell growth), S (DNA synthesis), G2 (preparation for division), and M (mitosis, where the cell actually divides).

Cell proliferation is crucial for various physiological processes, such as embryonic development, wound healing, and immune response. However, when the regulation of cell proliferation becomes disrupted, it can lead to pathological conditions like cancer. In cancer, cells proliferate uncontrollably due to mutations in genes that regulate the cell cycle, often resulting in tumor formation.