TSPAN7 and Parkinson disease: To understand the downstream gene expression modulated by the transcriptional repressor HDAC4 in our mitochondria-stressed cell model of PD, the core set of four HDAC4-controlled genes, including Tspan7, Atp1a3, Rtn1, and Prkcb (Lang et al., 2019), was analyzed by RT-qPCR.