Similarly, in the Purkinje cell degeneration (pcd) transgenic mouse model that exhibit progressive PC degeneration and ataxia, a significant increase in the expression of GRP78 was observed, along with the upregulation of ER stress-induced apoptosis markers CHOP and caspase 12, suggesting that the activation of UPR contributed to PC degeneration in pcd mouse model [57]. This evidence concerns the gene HSPA5 and pachyonychia congenita.