EPOR and anemia (phenotype): Furthermore, folic acid and a single shot therapy with steroids may improve hematopoiesis; it is a matter of debate whether erythropoiesis-stimulating agents (ESA) are useful for treatment of ruxolitinib-induced anemia, as erythropoietin receptor signals require functional JAK signalling; however, in a recent retrospective study it was shown that application of ESAs could improve anemia in ruxolitinib treated patients [41].