Fig. 6.

Inactivation of NQO1 increased acetyl α-tubulin levels but did not alter the NADH or NAD⁺concentrations in 16HBE cells. (A) Chemical structures of MI2321 and the non-inhibiting control indolequinone MI3190. (B) Acetyl α-tubulin levels and NQO1 catalytic activity were measured in 16HBE cells after treatment with MI2321 or MI3190 (1 μM) for 2 h. (C) Intracellular NADH and NAD⁺ concentrations were measured in 16HBE cells (n = 3) following treatment with MI2321 or MI3190 (1 μM) for 2 h. Treatment of 16HBE cells (n = 3) with 10 μM β-lapachone (β-LAP) or 10 μM β-LAP plus 5 μM olaparib (β-LAP + OLA) for 2 h were included as positive controls.