BCNU does not alter the activities of secretases. A) Partially purified β- and γ-secretase enzyme complexes from mouse brain homogenates were used to detect the activity of secretases using specific fluorogenic substrates. BCNU up to 40 μM did not inhibit the activities of either β- or γ-secretases. B) The activities of both ADAM17 and ADAM10 (α-secretase) were also not affected by BCNU at any of the concentrations tested. BCNU, 1, 3 bis (2-chloroethyl)-1-nitrosourea.