Fig. 1. en RNA and protein persist during prolonged hypoxia. Wild-type 5-h-old embryos were hybridized with an en probe to visualize RNA patterns (A–D), or stained with En antibody to reveal protein distribution (E–H) after exposure to different oxygen environments: normoxia (control) (A, E); 24 h hypoxia (B, F); 48 h hypoxia (C, G); 72 h hypoxia (D, H).