FIG. 4.

Gadd34-null erythrocytes are more resistant to hemolysis under severe hypotonic conditions and have normal life spans. (A) Wild-type (black bars) and Gadd34-null (white bars) erythrocyte hemolysis in decreasing salt concentrations, as determined by absorbance of released hemoglobin at 540 nm. Data are plotted as means for three mice from each genotype normalized to complete lysis (0.0% NaCl) ± standard errors of the mean. *, P < 0.05; **, P < 0.01. (B) Erythrocyte (RBC) half-life was determined by measuring the disappearance of NHS-biotin from circulating erythrocytes. The wild-type erythrocyte half-life was 17 days, and the Gadd34-null erythrocyte half-life was 21.6 days (P = 0.19).