Fig. 3. Wnt11 and Nkx2-5, but not MHC are direct targets of regulation by GATA4 and GATA6. RT-PCR analysis of Nkx2-5, Wnt11 and MHC gene expression in Xenopus animal cap explants that were injected with GATA4GR or GATA6GR RNA and cultured in the presence or absence of cycloheximide (CHX) and dexamethasone (Dex), as indicated. In A, 100 pg or 200 pg GATA4GR or GATA6GR mRNA were injected, as indicated; in B, 100 pg. (A) CHX followed by Dex treatment from stage 8 and analysis of gene expression at control stage 11. (B) CHX followed by Dex treatment from control stage 18 and analysis at stage 20. Activated GATA transcription factors induce Nkx2-5 and Wnt11, but not MHC gene expression in the presence of the protein synthesis inhibitor (CHX) at different stages, thereby identifying them as direct target genes of GATA transcription factors.