ALDH1A1 and Parkinson disease: Sox6+ and ALDH1A1+ DA neurons in the SNpc are selectively diminished in postmortem PD brains.[8] To test the possibility that active AEP might cut these crucial biomarkers in DA neurons, we conducted cellular experiments and found that rotenone dose‐dependently activated AEP, correlating with gradual escalation of both Sox6 and ALDH1A1 truncation in SH‐SY5Y cells, which were blocked by AEP inhibitor CP#11A (Figure S4A,B, Supporting Information).