Castelnovo showed that the neuroprotective action of P4 in a Parkinson’s disease human cell model is brought about the membrane progesterone receptor α (mPRα/PAQR7) [91], which is in good agreement with the previously obtained results since mPRs have been reported to mediate the neuroprotective effects of progestogens in different neuronal cell line models [92]. Here, PAQR7 is linked to Parkinson disease.