Fig. 5. High POP-1 blocks the myogenic activity, and promotes the hypodermal activity, of PAL-1. All embryos were treated with mex-3 RNAi that results in ectopic PAL-1 activity. After overnight incubation, embryos were assayed by antibody staining for the muscle marker MHC A and the hypodermal marker LIN-26. The upper pair of panels show representative focal planes of the robust myogenesis (MHC A) accompanying ectopic PAL-1 activity after co-depletion of POP-1 activity by RNAi; no LIN-26-positive cells are detected. In contrast, the lower pair of panels shows an embryo that was co-depleted of LIT-1 by RNAi to block the down-regulation of POP-1 by Wnt/MAP kinase signaling (see text). After overnight incubation, only a few cells (presumably from the D lineage) adopted a muscle-like fate whereas many cells adopted a hypodermal-like fate as seen in these images that are representative of focal planes throughout the embryo.