PINK1 and Parkinson disease: Notably, Pink1−/- mice, although having dysfunctional mitochondria, fail to experience neurodegeneration or significant motor impairment.13 An alternative function for PINK1 was recently discovered whereby it suppresses the presentation of mitochondrial peptides on MHC I to the immune system in response to bacterial lipopolysaccharide (LPS),14 suggesting that PINK1’s role in PD may be immunological and influenced by external factors.