Overexpression of both miR-21 and miR-196b blocks granulopoiesis in vitro. (A) Flow cytometric analysis with antibodies to 7/4 and F4/80 denoting neutrophil, mixed, and monocytic phenotypes of liquid cultures from Lin⁻ bone marrow cells transduced with MSCV vector encoding miR-21, miR-196b, miR-21, and miR-196b or a nontargeting shRNA control. (B) Cytospin from 4-day G-CSF–stimulated liquid cultures of panel A. Results are displayed as percentage of neutrophils, monocytes, and mixed (n = 3, mean ± SD).