 The CMP can then further differentiate into the megakaryocyte–erythroid progenitor cell (MEP), which goes on to make RBCs and platelets, or the granulocyte/macrophage progenitor (GMP), which gives rise to the granulocytes of the innate immune response.MEP differentiation was found to be contingent upon the transcription factor GATA1, whereas GMP differentiation needs SPI1.When expression of either was inhibited by morpholino in zebrafish, the other lineage programming pathway resulted.