Where does progesterone fit in?
Estrogen is the hormone that stimulates cell proliferation, or the growing phase. In other words, estrogen causes cells to divide and multiply. Progesterone, on the other hand, is the hormone that stops growth and stimulates ripening. It induces cell maturation and programmed cell death (called apoptosis). Although cells in different parts of the body may look and work differently, most repair and reproduce themselves in the same way. Normally, this division of cells takes place in an orderly and controlled manner. If, for some reason, the process gets out of control, the cells will continue to divide, developing into a lump which is called a tumour. Tumours can be either benign or malignant. Doctors can tell whether a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy. Whilst not a cure for cancer, progesterone can dramatically decreases cell multiplication rates, providing women with a degree of protection against estrogen-d
