PRKN and Parkinson disease: In light of the report that an increase of Ca2+ in cells leads to a sustained activation of the TAK1-JNK pathway (39), it is reasonable to speculate that irregularly mobilized Ca2+ may trigger the formation of a signal loop (like JNK-SARM1-Ca2+-TAK1-JNK) in a sustained manner, contributing to the pathological progression of PD in PARK2 patients.