How a Blood Cell Intracellular Signal Keeps Blood Flowing
The hormone erythropoietin (Epo) stimulates differentiation of bone-marrow erythroblasts into red cells by activating a binary intracellular Stat5 signal. In hypoxic stress, higher Epo increases red cell production by generating a graded Stat5 signal that reaches high intensities in early (large) erythroblasts.