RAP-536 proved to be effective in increasing erythropoiesis in normal mice, rats, and monkeys by enhancing maturation of late-stage erythroblasts, and was also able to reduce ineffective erythropoiesis and anemia in a mouse model of MDS, characterized by ineffective erythropoiesis, by inhibiting the overactivation of SMAD2/3 [26]. The gene discussed is SMAD2; the disease is anemia (phenotype).