Mechanisms of Inflammatory Cytokine Inhibition of Erythropoiesis in ACI. Three mechanisms (shown in red) that are mediated by inflammatory cytokines are key elements in the pathophysiology of ACI and represent potential therapeutic targets. The main period of erythropoiesis in which each of the respective mechanisms has its major effect is indicated by arrows. The stages of erythropoiesis begin with the hematopoietic stem cell (HSC) and extend through the mature erythrocyte (RBC). The periods of erythropoietin (EPO) dependency and hemoglobin synthesis are shown below those specific stages of differentiation.