ROCK1 and Parkinson disease: In vitro and in vivo studies demonstrate that Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) promotes aberrant mitochondrial fission and apoptosis dependent on dynamin-related protein 1 (DRP1) activation in 1-methyl-4-phenylpyridinium (MPP+)-treated PC12 cells, a cell culture model of PD.