SELENOK and neoplasm: Malignant tumor cells usually exhibit a strong dependence on cytosolic Ca2+ for disease progression.280–282 Inositol 1,4,5-trisphosphate (IP3) interacts with IP3R in the ER membrane to release Ca2+ from the ER lumen.283,284 Fredericks et al. found that selenoprotein K (SELENOK) forms a complex with ZDHHC6 on the ER membrane and promotes IP3R palmitoylation at C56 and C849, leading to IP3R protein stabilization and Ca2+ release.