This week’s episode covers recent research that provides new insights in erythropoiesis, mastocytosis, and chronic active EBV. First, we’ll review a report describing how interactions between an E3 ubiquitin ligase and a heterochromatin-associated protein may serve as a “toggle” of sorts to regulate the formation of red blood cells. Next, researchers find that presence of hereditary α tryptasemia may predict the risk of severe anaphylaxis in patients with mastocytosis. Finally, we’ll review a report revealing large numbers of myeloid-derived suppressor cells in patients with EBV-associated T/NK cell lymphoproliferative disorders, which may have important implications for understanding disease pathogenesis and targeted approaches to therapy.