Mouse Cby expression and a postnatal lethality of Cby^−/− mice. (A) Cby^+/+ E10.5 embryo hybridized with antisense (AS) Cby probe. (B) A single Cby transcript of 1.2 kb was detected by Northern blot analysis in the adult mouse tissues. (C) Cby^−/− E10.5 embryo hybridized with antisense Cby probe. (D) Cby^+/+ E10.5 embryo hybridized with Cby sense (S) probe. (E) P20 Cby^+/+ and Cby^−/− littermates. (F) Body weight analysis of Cby^−/− and control mice on a regular chow diet. The control group included three males and three females, whereas the Cby^−/− group had 28 animals at P2 that diminished to seven knockout-survive (KO-S) animals at the end of the study. Error bars represent SEM. (G) Kaplan-Meyer survival curves for Cby^+/+ (n = 15), Cby^+/− (n = 23), and Cby^−/− (n = 32) mice. KO, knockout; KO-D, knockout-die. Bars, 1 mm.