PCSK1 and Huntington disease: ST14A is an immortalized striatal cell line with medium spiny neurons (MSNs) characteristics72 and ST14A 8plx line stably expressing mutant Htt fragment was established as a cell model of HD.73, 74 Inhibition of death receptor signaling by zVAD-fmk, a pan-caspase inhibitor in apoptosis, leads to RIP1 kinase activation and cell death in ST14A and ST14A 8plx line cells, which can be almost completely rescued by Nec-1 (ref. 44) Unlike apoptosis, dying striatal cells showed atrophy and shrinkage of the cell body and had no caspase-3-specific cleavage.