TGFBR1 and Parkinson disease: The levels of TGFBR1, TGF-β1 and Nrf2 were determined in PD mice or cells, and the results in Figure 5(a) unveiled that MPTP or MPP+ induced significant increases in TGFBR1 and TGF-β1, and a reduction in Nrf2 than the sham (p < 0.001).