Identification of DJ-1-binding compounds and effects of DJ-1-binding compounds on oxidative stress-induced cell death. (A) SH-SY5Y cells were pretreated with 1 μM of each compound for 20 hours and then treated with H2O2 for 3 hours, and cell viability was measured by an MTT assay. ''-'' indicates cells not treated with compounds. Significance: ** P < 0.01 versus vehicle (DMSO) control without compounds. (B) Chemical structures of compound-23, -B and -D. (C) Binding of compounds to DJ-1 was examined by using a quartz crystal microbalance as described in Methods. Hz indicates decreased frequency of a sensor chip.