A third generation of self‐inactivating lentivirus vector (GeneChem, Shanghai, China) containing a CMV‐driven GFP reporter and a U6 promoter upstream of the cloning sites (Age I and EcoR I) was used for cloning shRNAs. The target sequence for rat MsrA was 5′‐AGCACGTCAGCTTTGAGGA‐3′ and for control scrambled shRNA was 5′‐TTCTCCGAACGTGTCACGT‐3′. PC12 cells were infected with lentivirus at a multiplicity of infection (MOI) of 20 for 8 h. Then, the medium was replaced with fresh complete medium. After 72 h, cells were observed under fluorescence microscopy to confirm that more than 80% of cells were GFP‐positive.