It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that bud off large numbers of platelets.

The protein encoded by this gene is a humoral growth factor necessary for megakaryocyte proliferation and maturation, as well as for thrombopoiesis.

Abnormalities in this gene occur in some hereditary forms of thrombocytosis (high platelet count) and in some cases of leukemia.

Small amounts are also made by striated muscle and bone marrow stromal cells.

On the other hand, high platelet and megakaryocyte concentrations lead to more thrombopoetin destruction and thus less availability of thrombopoietin to bone marrow.

It promotes apoptosis of newly generated neurons, an effect counteracted by EPO and neurotrophins.