Disclosed are methods of modulating erythropoiesis with arginine vasopressin receptor 1B (AVPR1B) molecules, such as AVPR1B agonists or antagonists. In one example, a method of stimulating erythropoiesis is disclosed including administering an effective amount of an AVPR1B stimulatory molecule to a subject in need thereof, thereby stimulating erythropoiesis. Also disclosed is a method of stimulating hematopoetic stem cell (HSC) proliferation which includes administering an effective amount of an AVPR1B stimulatory molecule to a subject in need thereof, thereby stimulating HSC proliferation. A method of inhibiting HSC proliferation including administering an effective amount of an AVPR1B inhibitory molecule to a subject in need thereof, thereby inhibiting HSC proliferation is provided.
