Overexpression of miR-cluster 99b/let-7e/125a or miR-125a alone fixes HSPCs in a primitive state. (A) Schematic representation of the retroviral vectors used to overexpress miR-cluster 99b/let-7e/125a, miR-125a and miR-155. (B) Quantitative RT-PCR data showing the expression levels of the miR-cluster 99b/let-7e/125a members and miR-155 on overexpression relative to the endogenous control snoRNA202. Shown is the mean ± SD. (C) CAFC data showing the number of HSPCs.