The finding challenges two long-standing assumptions in the field: first, that ATPIF1’s role in erythropoiesis is conserved across vertebrates derived from the observation of non-compensatory severe anemia in ATPIF1-deficient zebrafish (Shah et al., 2012); and second, that splenic erythropoiesis only execute a stress-specific erythropoiesis and cannot replace BM erythropoietic programs (Menon et al., 2024). Here, ATP5IF1 is linked to anemia (phenotype).