 It restricts the cell cycle of immature cells by inhibition of CDK2 and CDK4 and promotes granulocytic differentiation.Steady state production of granulocytes is activated after the engulfment of apoptotic granulocytes by tissue macrophages.Steady state granulopoiesis is switched to a program termed emergency granulopoiesis after a major insult to the organism, usually a bacterial infection.