PATHOLOGY

Detailed explanation-1: -External regulators-proteins that respond to events outside the cell.-speed up or slow down the cell cycle. Growth factors-external regulators that stimulate the growth and division of cells.

Detailed explanation-2: -Growth factors are external regulatory proteins that slow down the cell cycle.

Detailed explanation-3: -is the term for a class of gene products that play important roles in the regulation of cell division and tissue proliferation. Each growth factor has a specific cell-surface receptor. Binding of the growth factor to the receptor initiates or, in some cases, blocks cell division.

Detailed explanation-4: -External factors There are external physical and chemical signals that help regulate the cell cycle. For example, a cell that is surrounded by other cells stops dividing. Many cells also release chemical signals that tell other cells to grow. Growth factors are proteins that stimulate* cell division.