THE MAMMALIAN-CELL CYCLE IN NORMAL AND ABNORMAL GROWTH

Cell division, a complex array of intracellular events, occurs in a hi ghly ordered and carefully coordinated manner. This regulation is achi eved by the sequential activation and deactivation of the members of a family of serine-threonine-specific protein kinases that consist of r egulatory and enzymatic subunits, the cyclins and cyclin-dependent kin ases. These enzymes, in turn, regulate the activity of other proteins involved in the mitogenic pathway. Mutations in the components of the regulatory pathways can lead to aberrant growth, including malignancie s.