Fetal megakaryocytes express high levels of Lin28B and Hmga2 transcripts, as well as several other known Lin28b/Let-7 target genes. (A) Transcript levels of Lin28B relative to small ribosomal subunit 18S (18S) in cultured megakaryocytes from E12.5 fetal livers or adult bone marrow. Significance was determined using an unpaired 2-tailed Student t test *P < .0001; n = 3. (B) Transcript levels of high-mobility group AT-hook 2 (Hmga-2) relative to 18S in cultured megakaryocytes from embryonic day 12.5 fetal livers or adult bone marrow. Significance was determined using an unpaired 2-tailed Student t test *P < .0001; n = 3. (C) Transcript levels of Igf2bp1, Igf2bp2, Igf2bp3, and Arid3 relative to 18S in cultured megakaryocytes from E12.5 fetal livers or adult bone marrow. Significance was determined using 2-way ANOVA. *P < .0001; n = 3.