CDKN1A and Parkinson disease: (4) CDKN1A activated kinases PAK6 and PAK4; PAK4 prevents caspase activation and thus apoptosis (Gnesutta et al. 2001; Gnesutta and Minden 2003) and its neuroprotective function was recently shown in a rat model of Parkinson's disease (Won et al. 2016).