KEAP1 and Parkinson disease: Intriguingly, the expression of KEAP1 (NRF2 inhibitor) was also found to be increased in PD SN (Fig. 2B, GSE7621; Additional file 1: Fig. S3B, GSE26297), possibly suggesting compensatory NRF2-Keap1 autoregulation [53] (elaborated in “Discussion” section).