Altered proteolytic activity and secretion of MT-HNE in U937T cells. (A) Proteolytic activity of WT-HNE or MT-HNE in U937T cells using the chromogenic substrates suc-Ala-Ala-Ala-pNA (▴) and suc-Tyr-Leu-Val-pNA (□). Relative activity of HNE was defined as the difference between activity with and without promoter induction and was normalized to the amount of HNE protein synthesized (determined by immunoblotting). Data are given as mean ± SD. (B) Secretion of WT-HNE or MT-HNE from U937T cells. Relative secretion was defined as the difference between secretion with and without promoter induction and was normalized to the amount of total HNE protein synthesized (determined by immunoblotting). Data are given as mean ± SD.