HMOX1 and Parkinson disease: To elucidate the role of the Nrf2/HO-1 pathway in the in vitro PD cell model, si-Nrf2 was applied to silence Nrf2, so as to explore the role of HOTAIRM1 knockdown in the Nrf2/HO-1 pathway in MPP+-induced SH-SY5Y cell oxidative stress (all p < 0.01, Figure 6(a) and (b)).