SPINSTER, also known as SPNS1 or SPIN1, is a 528 amino acid multi-pass membrane protein that localizes to the inner mitochondrial membrane and belongs to the spinster subfamily of the major facilitator superfamily (1). SPINSTER interacts with Bcl-x and Bcl-2 and, via this interaction, is thought to be involved in necrotic or autophagic cell death (2). The related protein SPNS2 is critical for the normal lymphocyte localization and mammalian immune system function (1,3).