TMEM97 and neoplasm: Ligands acting at the sigma-2 receptors have mostly antitumor actions, being the sigma-2 subtype overexpressed in tumor cells where it regulates cell death through different pathways (Wheeler et al., 2000; Hornick et al., 2012a; Hornick et al., 2012b; Zeng et al., 2012; Pati et al., 2017b).