CiMRF expression in the endoderm activates muscle-specific genes. Embryo in A was electroporated with pTTFLacZ and assayed for TnI; all other embryos were electroporated with pFCiMRFb and assayed for TnI (B), SMYD1 (C), TPM2 (D), or Actin (E, F). Embryos A-D are shown in lateral view, and embryos in E and F are shown in ventral view. Size bar is 50μm, and all embryos shown are C. intestinalis.