Promotion of liver tumors by steroid hormones

Corticosterone inhibits proliferation of rat liver cells, but it can be inactivated by blocking its cytoplasmic receptors in liver cells with other steroids (progesterone). High levels of progesterones in animals lead to stimulated proliferation in the liver. Abnormally high proliferation in the liver may promote malignant transformation or may make it possible for smaller amounts of hepatocarcinogenic substances to induce tumors in a shorter time than normal.