Enforced expression of miR-146a does not affect megakaryopoiesis in vitro. Fetal liver progenitors were infected with MSCV retroviruses encoding miR-146a or empty vector as control, then analyzed after 4 days of culture in thrombopoietin under puromycin selection. (A) CD41 and CD42 expression on cultured megakaryocytes. (B) Relative miR-146a expression analyzed by Q-PCR. (C) Megakaryocyte morphology. Cytospin preparation of megakaryocytes stained with May-Grunwald Giemsa. Scale bar = 10 μm. Photos were taken using a Leica DMLB microscope, Leica DFC420 digital camera, and Leica Application Suite software Version 2.7.1 R1. Original magnification 200×. Lens, Leica NPlan 20×, numerical aperture 0.40. (D) Relative expression of megakaryocyte marker genes determined by real-time RT-PCR. Control cells (transduced with empty vector) are assigned an arbitrary value of 1.