RIPK1 and Parkinson disease: In the postmortem substantia nigra of individuals with PD, the expression of receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed-lineage kinase domain-like protein (MLKL) is elevated, and mutated LRRK2 proteins are positively associated with the activation of MLKL and necroptosis [251,252].