Taira et al. (2004) further reported that overexpression of DJ-1 in neuroblastoma cells leads to a reduction in ROS accumulation and hypothesized that DJ-1 may harbor antioxidant activity in vivo. In contrast, we find that ES cells that are deficient in DJ-1 display a normal initial burst of ROS in the context of H2O2. Consistent with this, we fail to detect DJ-1 antioxidant activity in vitro (Shendelman et al. 2004). This evidence concerns the gene PARK7 and neuroblastoma.