Properties of amino-terminally truncated NE. (A) Mutant forms of NE are unable to cleave MeO-Suc-Ala-Ala-Pro-Val-pNA, an NE-specific substrate after a 16 hour incubation, except for c.1A>G which showed minimal residual activity. Data shown are mean ± standard deviation of 3 independent experiments. (B) No significant difference in ER stress was observed, as measured by HSPA5 expression. Data shown are mean ± standard deviation of 3 independent experiments. (C) There is no observed increase in apoptosis, as measured by Annexin V staining. Mean ± standard deviations of 2 independent experiments are shown. *P < .05 vs GFP.