HSA-deficient erythrocytes are more susceptible to hypotonic lysis. Hemoglobin (measured by absorbance at 550 nm) released from erythrocytes incubated at various tonicities was determined for both HSA+/+ and HSA-/- erythrocytes. The data points are the averages and standard deviations of three mice and the results are representative of three independent experiments (a total of nine mice).