Osmotic resistance curves of red blood cells from wild type and anxA7-/- mutant mice. The osmotic resistance towards changes in the extracellular ionic strength is a convenient assay for analysis of the red blood cell integrity. It is measured as a sodium chloride concentration in which cellular lysis starts (minimal resistance) up to a complete lysis (maximal resistance) of a red blood cell. The osmotic resistance of annexin A7 deficient red blood cells is significantly increased compared to the one of wild type (p = 0.00066; n = 8).