"Let"-ing go with clonal expansion?

In this issue of Blood, Ikeda et al report the effects of the high mobility group A2 (Δhmga2) lacking the 3' untranslated region (UTR) in hematopoietic tissues. Overexpression of Δhmga2 in transgenic mice resulted in "big mice with big blood": the mice weighed more and had a myeloproliferative phenotype with increases in peripheral blood counts, splenomegaly, a hypercellular bone marrow and erythropoietin-independent erythroid colony formation.