Hematopoietic progenitor colony assays from fetal liver and yolk sacs of Zfp36l2 WT, heterozygous, and KO embryos. Fetal liver cells (A) isolated from E14.5 embryos (WT, n = 15; heterozygous, n = 26, KO, n = 14) and yolk sac cells (B) isolated from E11.5 embryos (WT, n = 5; heterozygous, n = 10; KO, n = 5) were grown in methylcellulose-based medium as described in “Colony-forming cell assays.” The numbers of CFU-GM, BFU-E, and CFU-GEMM, and CFU-GM/M per fetal liver or yolk sac were determined after 7 days of culture. (C) Yolk sac cells isolated from E8 to E8.25 embryos (WT, n = 20; heterozygous, n = 31; KO, n = 10) were grown in methylcellulose-based medium. Primitive erythroid progenitor colonies, EryP-colony–forming cells (C) were determined after 5 days in culture. Values are mean ± SEM. Statistical significance was determined using one-way analysis of variance with Tukey HSD post hoc test: *P < .05; **P < .01; ****P < .001.