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Fig. 7 Early treatment with the MEK-inhibitor CI-1040 rescued leftward heart displacement and cilia length in embryos expressing NS and LS Shp2 variants. Embryos were injected with mRNA encoding WT-Shp2 (Shp2), Shp2-D61G and Shp2-A462T at the one-cell stage. (A-F) Representative images of bud stage embryos are depicted. The shape of the NS- and LS-Shp2-expressing embryos is restored by treatment with 0.25µM CI-1040 at 4.5hpf for 1h. (G) The ratio between the length of the major and minor axes was determined as quantitative measure of the epiboly defects in NS- and LS-Shp2-expressing embryos. Averages are depicted with error bars indicating s.e.m. Statistical significance was determined using Student′s t-test (**P<0.01; ***P<0.001). (H) Embryos were treated with MEK inhibitor CI-1040 (0.25µM) for 1h at 4.5hpf or mock-treated with DMSO and lysed at 10hpf. Immunoblots of the zebrafish lysates were stained using antibodies specific for pErk and Erk. The experiment was repeated three times and representative blots are depicted here. (I-K) Embryos were mock treated with DMSO (I) or with CI-1040 for 1h at 4.5hpf (J) or at 10hpf (K). Heart displacement was determined in embryos following in situ hybridization with a myl7-specific probe as in Fig. 4. Histograms represent the percentage of embryos with heart displacement to the left, middle or right. The total number of embryos (n) is indicated.