The Lin28–let-7 axis during myeloerythropoiesis. (A) FL or adult BM CMPs were isolated by FACS. The level of Lin28b mRNA was measured by qPCR in E14.5 FL or BM CMPs, and the levels were compared with mouse embryonic stem (ES) cells by qPCR. *, P < 0.0001 by Student’s t test. n = 6 replicates for FL and BM each over two experiments. An 8.08-fold expression increase in Lin28b was observed in FL CMPs compared with adult BM CMPs; P = 2.34 × 10⁻¹⁵ by RNAseq. (B) Scatter plot of differentially expressed genes between FL and adult BM CMPs as measured by RNAseq. Predicted let-7 targets with significantly different expression between FL and adult BM CMPs at an FDR of 0.001 are indicated in red. Pertinent transcripts are denoted. n = 3 biological replicates over at least two separate sorting experiments for BM and FL. (C–E) Levels of the indicated mature let-7 microRNA family members (C), Let7bhg (D), or let-7 precursors (E) were measured by qPCR in FACS-sorted FL or adult BM CMPs. The results are presented as fold expression compared with FL, normalized to an expression value of 1. *, P < 0.05. n = 6 embryos/mice sorted from three independent experiments. Error bars represent SEM.