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FIGURE 3 Smad3 inhibition has limited effects on sarcomere disassembly and cardiogenic factor reactivation during regeneration. (A–D′) Representative fluorescence images of Tg(vmhc:mCherry-NTR; myl7:actinin-eGFP) hearts at 4 dpf/1 dpt indicate that sarcomere disassembly occurred in the ablated hearts (C,C′) and SIS3-treated ablated hearts (D,D′). (A′–D′) Enlargement of box areas in panels (A–D), green channel only. (E–P) Whole-mount in situ hybridization showing the expression level changes of cardiogenic factors nkx2.5, gata4, and tbx5a during regeneration. Smad3 inhibition via SIS3 treatment could abolish the reactivation of nkx2.5 at 5 dpf/2 dpt (G,H) but has no effect on the reactivation of gata4 and tbx5a (K,L,O,P). Dashed lines outline the hearts. Scale bars (A–D,E–P) 50 μm and (A′–D′) 20 μm. dpf, days post-fertilization; dpt, days post-treatment; atr., atrium; oft., out flow tract; vent., ventricle.