HTRA2 and Parkinsonism: Although loss of Omi/Htr2A is neuroprotective (Martins et al., 2002), and Omi/Htr2A has been linked to Parkinson’s (Strauss et al., 2005) suggesting important roles in controlling neuron apoptosis, it is not clear whether non-apoptotic caspase activity involves the release of Omi/Htr2A (or Smac/Diablo).