ERG synergizes with Gata1s to promote transient megakaryocytic proliferation presenting a human TMD expression profile. (A-C) FL cells were isolated from E12.5 (A-B) and E14.5 (C) wild-type, TgERG embryos and males and females of Wt/Gata1s and ERG/Gata1s embryos. The cells were plated on methylcellulose supplemented with TPO to promote the growth of megakaryocytic colonies (CFU-MK). MK colonies were counted 5 to 7 days following plating. Each bar graph represents the average of at least 3 independent experiments. (D) Representative figure of megakaryocytic colonies from (top) TgERG, (middle) Wt/Gata1s, and (bottom) ERG/Gata1s FLs. (E) Real-time PCR of common human TMD genes (11). *Statistical significance was tested using the t test (P = .028 for Mpl; P = .009 for Pecam1; and P = .0 for Mycn). (F) Gene set enrichment analysis (GSEA) using gene expression of E14.5 ERG/Gata1s FL cells (GSE46481) compared with the respective Wt control shows significant enrichment of genes that were upregulated in human TMD (GSE4119). NES and FDR q values are shown. (G) Heat map showing the core enrichment genes from the GSEA presented in panel F. (H) Hepatic fibrosis in ERG/Gata1s male FL. Reticulin staining (arrowheads) of (left) Wt/Gata1s and (right) ERG/Gata1s FL tissues (magnification, ×400). (I) Transient thrombocytosis in TgERG and ERG/Gata1s mice. Platelet counts were retrieved from male and female TgERG and ERG/Gata1s and their Wt and Wt/Gata1s littermates at 3 and 7 weeks of age; n= at least 6 for each group. A significant difference was found between TgERG and Wt and between ERG/Gata1s and Wt/Gata1s (t test: P < .017, P < .0031, respectively). FDR, false detection rate; NES, normalized enrichment score.