Lifeact-EGFP is expressed at early embryonic stages and has comparable signal-to-noise to Phalloidin. (A) The Lifeact-EGFP signal matches Phalloidin labeling of the actin cytoskeleton in the primitive streak at HH3. (B) There is no significant difference in the signal-to-noise of the Lifeact-EGFP and Phalloidin staining of fixed embryos in Fig. 1 (n = 7 ROIs from three embryos, Welch’s two-sided t test).