In the steady state, deletion of Dok2 (a known tyrosine downstream of CD200R signaling) has been associated with leukemia and expansion of hematopoietic stem cells.26 However, CD200-deficient mice are not characterized by expansion of BM progenitors in the steady state.27 This indicates that CD200 deletion per se is not sufficient to induce changes in myelopoiesis. The gene discussed is CD200R1; the disease is leukemia.