This protocol outlines a method for quantifying gene expression in tissue samples from the ventral midbrain, specifically the substantia nigra pars compacta (SNpc). The process involves RNA extraction, reverse transcription, and real-time quantitative PCR (qPCR) using TaqMan Assay Reagents. Key steps include homogenizing tissue samples with QIAzol Lysis Reagent, isolating total RNA using the RNeasy Lipid Tissue Kit, and performing cDNA synthesis with the Retroscript Kit. Real-time PCR is conducted on a Step One Detection System, and the results are normalized using the housekeeping gene β-actin. The protocol also includes instructions for processing cell samples and quantifying RNA using a NanoDrop ND-100. The final step involves calculating the relative fold changes in target gene expression compared to wild-type (WT) controls.This protocol outlines a method for quantifying gene expression in tissue samples from the ventral midbrain, specifically the substantia nigra pars compacta (SNpc). The process involves RNA extraction, reverse transcription, and real-time quantitative PCR (qPCR) using TaqMan Assay Reagents. Key steps include homogenizing tissue samples with QIAzol Lysis Reagent, isolating total RNA using the RNeasy Lipid Tissue Kit, and performing cDNA synthesis with the Retroscript Kit. Real-time PCR is conducted on a Step One Detection System, and the results are normalized using the housekeeping gene β-actin. The protocol also includes instructions for processing cell samples and quantifying RNA using a NanoDrop ND-100. The final step involves calculating the relative fold changes in target gene expression compared to wild-type (WT) controls.